sphinx: import sphinx docs

The Bitbake manual was migrated to Sphinx in Yocto Project 3.2. Since
the docs between 3.2 and 3.1 are "similar", and since 3.1 is an LTS
release, we agreed to backport the documentation onto 3.1.

If we look at all docs changes in 3.1 and 3.2, we have the following:

=== Changes in 3.1
git log --oneline b94dec477a8d48ebceec91952ba290798c56c1f5..origin/1.46 -- doc/
====
324aaa7f bitbake-user-manual-metadata.xml: fix a minor error
f92e19a3 doc: More explanation to tasks that recursively depend on themselves
e4695176 doc: Clarify how task dependencies relate to RDEPENDS
25c5c79b user manual: properly tag content as <replaceable>
be367887 docs: delete reference to obsolete recipe-depends.dot

=== Changes in 3.2/master
git log --oneline b94dec477a8d48ebceec91952ba290798c56c1f5..origin/master -- doc/
====
a7c47f1e sphinx: rename Makefile.sphinx
427721d8 sphinx: remove DocBook files
d52190ea docs: static: theme_overrides.css: fix responsive design on <640px screens
9ae5cce7 docs: sphinx: report errors when dependencies are not met
ec4c481a docs: update README file after migrationg to Sphinx
c87cc35a docs: sphinx: replace special quotes with double quotes
ebdeef2c docs: ref-variables: add links to terms in glossary
29081375 bitbake-user-manual: fix bad links
a0f37789 sphinx: theme_override: Use bold for emphasis text
cbc5ca48 sphinx: theme_override: properly set font for verbatim text
08b1ae23 sphinx: remove leading '/'
99ba6fe9 sphinx: update style for important, caution and warnings
d99760cc sphinx: last manual round of fixes/improvements
4f94633a sphinx: bitbake-user-manual: insert additional blank line after title
63adcaa5 sphinx: add releases page
3e940d93 sphinx: conf: enable extlinks extension
9921c652 sphinx: index: move the boilerplate at the end of the page
4e461224 sphinx: add SPDX headers
cb19159c sphinx: Enhance the sphinx experience/nagivation with:
10a54678 sphinx: tweak html output a bit
219b2348 sphinx: Makefile.sphinx: add clean and publish targets
35fdc185 sphinx: fixes all remaining warnings
e11d2dd1 sphinx: fix links inside notes
57300955 sphinx: fixup for links
fa304c01 sphinx: override theme CSS
29af1cd2 sphinx: switch to readthedocs theme
e8359fd8 sphinx: bitbake-user-manual: use builtin sphinx glossary
6bf6c8d6 sphinx: initial sphinx support
84ccba0f sphinx: add initial build infrastructure
44b57216 bitbake-user-manual: update perforce fetcher docs
9186ca47 bitbake-user-manual: Add BBFILES_DYNAMIC
7689fa78 bitbake-user-manual: Remove TERM from BB_HASHBASE_WHITELIST example
06b5cf0a bitbake-user-manual-metadata.xml: fix a minor error
c92a266c doc: More explanation to tasks that recursively depend on themselves
caf42243 doc: Clarify how task dependencies relate to RDEPENDS
647c13d4 user manual: properly tag content as <replaceable>
2effbb6e docs: delete reference to obsolete recipe-depends.dot

We can conclude the following commits exist in 3.2 and not in 3.1 (if
we filter out sphinx changes)

44b57216 bitbake-user-manual: update perforce fetcher docs
9186ca47 bitbake-user-manual: Add BBFILES_DYNAMIC
7689fa78 bitbake-user-manual: Remove TERM from BB_HASHBASE_WHITELIST example

Out of these 3 changes, the following patches are for 3.2 only:
44b57216 bitbake-user-manual: update perforce fetcher docs
7689fa78 bitbake-user-manual: Remove TERM from BB_HASHBASE_WHITELIST example

To backport the Sphinx docs, we then need to cherry-pick all docs
patches from 3.2/1.48 and 'undo' the two patches above.

This first patch is the first step that imports all Sphinx files, and
remove Docbook files. It was done with the following command:

git cherry-pick -n \
 $(git log --reverse --oneline \
 b94dec477a8d48ebceec91952ba290798c56c1f5..origin/master -- doc/ \
 | cut -f1 -d' ')

Signed-off-by: Nicolas Dechesne <nicolas.dechesne@linaro.org>

2 files changed, 395 insertions, 0 deletions

diff --git a/doc/sphinx-static/switchers.js b/doc/sphinx-static/switchers.js
new file mode 100644
index 000000000..32113cfa9
--- /dev/null
+++ b/doc/sphinx-static/switchers.js
@@ -0,0 +1,233 @@
+(function() {
+  'use strict';
+
+  var all_versions = {
+    'dev': 'dev (3.2)',
+    '3.1.2': '3.1.2',
+    '3.0.3': '3.0.3',
+    '2.7.4': '2.7.4',
+  };
+
+  var all_doctypes = {
+      'single': 'Individual Webpages',
+      'mega': "All-in-one 'Mega' Manual",
+  };
+
+  // Simple version comparision
+  // Return 1 if a > b
+  // Return -1 if a < b
+  // Return 0 if a == b
+  function ver_compare(a, b) {
+    if (a == "dev") {
+       return 1;
+    }
+
+    if (a === b) {
+       return 0;
+    }
+
+    var a_components = a.split(".");
+    var b_components = b.split(".");
+
+    var len = Math.min(a_components.length, b_components.length);
+
+    // loop while the components are equal
+    for (var i = 0; i < len; i++) {
+        // A bigger than B
+        if (parseInt(a_components[i]) > parseInt(b_components[i])) {
+            return 1;
+        }
+
+        // B bigger than A
+        if (parseInt(a_components[i]) < parseInt(b_components[i])) {
+            return -1;
+        }
+    }
+
+    // If one's a prefix of the other, the longer one is greater.
+    if (a_components.length > b_components.length) {
+        return 1;
+    }
+
+    if (a_components.length < b_components.length) {
+        return -1;
+    }
+
+    // Otherwise they are the same.
+    return 0;
+  }
+
+  function build_version_select(current_series, current_version) {
+    var buf = ['<select>'];
+
+    $.each(all_versions, function(version, title) {
+      var series = version.substr(0, 3);
+      if (series == current_series) {
+        if (version == current_version)
+            buf.push('<option value="' + version + '" selected="selected">' + title + '</option>');
+        else
+            buf.push('<option value="' + version + '">' + title + '</option>');
+
+        if (version != current_version)
+            buf.push('<option value="' + current_version + '" selected="selected">' + current_version + '</option>');
+      } else {
+        buf.push('<option value="' + version + '">' + title + '</option>');
+      }
+    });
+
+    buf.push('</select>');
+    return buf.join('');
+  }
+
+  function build_doctype_select(current_doctype) {
+    var buf = ['<select>'];
+
+    $.each(all_doctypes, function(doctype, title) {
+      if (doctype == current_doctype)
+        buf.push('<option value="' + doctype + '" selected="selected">' +
+                 all_doctypes[current_doctype] + '</option>');
+      else
+        buf.push('<option value="' + doctype + '">' + title + '</option>');
+    });
+    if (!(current_doctype in all_doctypes)) {
+        // In case we're browsing a doctype that is not yet in all_doctypes.
+        buf.push('<option value="' + current_doctype + '" selected="selected">' +
+                 current_doctype + '</option>');
+        all_doctypes[current_doctype] = current_doctype;
+    }
+    buf.push('</select>');
+    return buf.join('');
+  }
+
+  function navigate_to_first_existing(urls) {
+    // Navigate to the first existing URL in urls.
+    var url = urls.shift();
+
+    // Web browsers won't redirect file:// urls to file urls using ajax but
+    // its useful for local testing
+    if (url.startsWith("file://")) {
+      window.location.href = url;
+      return;
+    }
+
+    if (urls.length == 0) {
+      window.location.href = url;
+      return;
+    }
+    $.ajax({
+      url: url,
+      success: function() {
+        window.location.href = url;
+      },
+      error: function() {
+        navigate_to_first_existing(urls);
+      }
+    });
+  }
+
+  function get_docroot_url() {
+    var url = window.location.href;
+    var root = DOCUMENTATION_OPTIONS.URL_ROOT;
+
+    var urlarray = url.split('/');
+    // Trim off anything after '/'
+    urlarray.pop();
+    var depth = (root.match(/\.\.\//g) || []).length;
+    for (var i = 0; i < depth; i++) {
+      urlarray.pop();
+    }
+
+    return urlarray.join('/') + '/';
+  }
+
+  function on_version_switch() {
+    var selected_version = $(this).children('option:selected').attr('value');
+    var url = window.location.href;
+    var current_version = DOCUMENTATION_OPTIONS.VERSION;
+    var docroot = get_docroot_url()
+
+    var new_versionpath = selected_version + '/';
+    if (selected_version == "dev")
+        new_versionpath = '';
+
+    // dev versions have no version prefix
+    if (current_version == "dev") {
+        var new_url = docroot + new_versionpath + url.replace(docroot, "");
+        var fallback_url = docroot + new_versionpath;
+    } else {
+        var new_url = url.replace('/' + current_version + '/', '/' + new_versionpath);
+        var fallback_url = new_url.replace(url.replace(docroot, ""), "");
+    }
+
+    console.log(get_docroot_url())
+    console.log(url + " to url " + new_url);
+    console.log(url + " to fallback " + fallback_url);
+
+    if (new_url != url) {
+      navigate_to_first_existing([
+        new_url,
+        fallback_url,
+        'https://www.yoctoproject.org/docs/',
+      ]);
+    }
+  }
+
+  function on_doctype_switch() {
+    var selected_doctype = $(this).children('option:selected').attr('value');
+    var url = window.location.href;
+    if (selected_doctype == 'mega') {
+      var docroot = get_docroot_url()
+      var current_version = DOCUMENTATION_OPTIONS.VERSION;
+      // Assume manuals before 3.2 are using old docbook mega-manual
+      if (ver_compare(current_version, "3.2") < 0) {
+        var new_url = docroot + "mega-manual/mega-manual.html";
+      } else {
+        var new_url = docroot + "singleindex.html";
+      }
+    } else {
+      var new_url = url.replace("singleindex.html", "index.html")
+    }
+
+    if (new_url != url) {
+      navigate_to_first_existing([
+        new_url,
+        'https://www.yoctoproject.org/docs/',
+      ]);
+    }
+  }
+
+  // Returns the current doctype based upon the url
+  function doctype_segment_from_url(url) {
+    if (url.includes("singleindex") || url.includes("mega-manual"))
+      return "mega";
+    return "single";
+  }
+
+  $(document).ready(function() {
+    var release = DOCUMENTATION_OPTIONS.VERSION;
+    var current_doctype = doctype_segment_from_url(window.location.href);
+    var current_series = release.substr(0, 3);
+    var version_select = build_version_select(current_series, release);
+
+    $('.version_switcher_placeholder').html(version_select);
+    $('.version_switcher_placeholder select').bind('change', on_version_switch);
+
+    var doctype_select = build_doctype_select(current_doctype);
+
+    $('.doctype_switcher_placeholder').html(doctype_select);
+    $('.doctype_switcher_placeholder select').bind('change', on_doctype_switch);
+
+    if (ver_compare(release, "3.1") < 0) {
+      $('#outdated-warning').html('Version ' + release + ' of the project is now considered obsolete, please select and use a more recent version');
+      $('#outdated-warning').css('padding', '.5em');
+    } else if (release != "dev") {
+      $.each(all_versions, function(version, title) {
+        var series = version.substr(0, 3);
+        if (series == current_series && version != release) {
+          $('#outdated-warning').html('This document is for outdated version ' + release + ', you should select the latest release version in this series, ' + version + '.');
+          $('#outdated-warning').css('padding', '.5em');
+        }
+      });
+    }
+  });
+})();
diff --git a/doc/sphinx-static/theme_overrides.css b/doc/sphinx-static/theme_overrides.css
new file mode 100644
index 000000000..e362677a7
--- /dev/null
+++ b/doc/sphinx-static/theme_overrides.css
@@ -0,0 +1,162 @@
+/*
+    SPDX-License-Identifier: CC-BY-2.0-UK
+*/
+
+body {
+  font-family: Verdana, Sans, sans-serif;
+  margin:  0em auto;
+  color: #333;
+}
+
+h1,h2,h3,h4,h5,h6,h7 {
+  font-family: Arial, Sans;
+  color: #00557D;
+  clear: both;
+}
+
+h1 {
+  font-size: 2em;
+  text-align: left;
+  padding: 0em 0em 0em 0em;
+  margin: 2em 0em 0em 0em;
+}
+
+h2.subtitle {
+  margin: 0.10em 0em 3.0em 0em;
+  padding: 0em 0em 0em 0em;
+  font-size: 1.8em;
+  padding-left: 20%;
+  font-weight: normal;
+  font-style: italic;
+}
+
+h2 {
+  margin: 2em 0em 0.66em 0em;
+  padding: 0.5em 0em 0em 0em;
+  font-size: 1.5em;
+  font-weight: bold;
+}
+
+h3.subtitle {
+  margin: 0em 0em 1em 0em;
+  padding: 0em 0em 0em 0em;
+  font-size: 142.14%;
+  text-align: right;
+}
+
+h3 {
+  margin: 1em 0em 0.5em 0em;
+  padding: 1em 0em 0em 0em;
+  font-size: 140%;
+  font-weight: bold;
+}
+
+h4 {
+  margin: 1em 0em 0.5em 0em;
+  padding: 1em 0em 0em 0em;
+  font-size: 120%;
+  font-weight: bold;
+}
+
+h5 {
+  margin: 1em 0em 0.5em 0em;
+  padding: 1em 0em 0em 0em;
+  font-size: 110%;
+  font-weight: bold;
+}
+
+h6 {
+  margin: 1em 0em 0em 0em;
+  padding: 1em 0em 0em 0em;
+  font-size: 110%;
+  font-weight: bold;
+}
+
+em {
+  font-weight: bold;
+}
+
+.pre {
+  font-size: medium;
+  font-family: Courier, monospace;
+}
+
+.wy-nav-content a {
+  text-decoration: underline;
+  color: #444;
+  background: transparent;
+}
+
+.wy-nav-content a:hover {
+  text-decoration: underline;
+  background-color: #dedede;
+}
+
+.wy-nav-content a:visited {
+  color: #444;
+}
+
+[alt='Permalink'] { color: #eee; }
+[alt='Permalink']:hover { color: black; }
+
+@media screen {
+    /* content column
+     *
+     * RTD theme's default is 800px as max width for the content, but we have
+     * tables with tons of columns, which need the full width of the view-port.
+     */
+
+    .wy-nav-content{max-width: none; }
+
+    /* inline literal: drop the borderbox, padding and red color */
+    code, .rst-content tt, .rst-content code {
+        color: inherit;
+        border: none;
+        padding: unset;
+        background: inherit;
+        font-size: 85%;
+    }
+
+    .rst-content tt.literal,.rst-content tt.literal,.rst-content code.literal {
+        color: inherit;
+    }
+
+    /* Admonition should be gray, not blue or green */
+    .rst-content .note .admonition-title,
+    .rst-content .tip .admonition-title,
+    .rst-content .warning .admonition-title,
+    .rst-content .caution .admonition-title,
+    .rst-content .important .admonition-title {
+        background: #f0f0f2;
+        color: #00557D;
+
+    }
+
+    .rst-content .note,
+    .rst-content .tip,
+    .rst-content .important,
+    .rst-content .warning,
+    .rst-content .caution  {
+        background: #f0f0f2;
+    }
+
+    /* Remove the icon in front of note/tip element, and before the logo */
+    .icon-home:before, .rst-content .admonition-title:before {
+        display: none
+    }
+
+    /* a custom informalexample container is used in some doc */
+    .informalexample {
+        border: 1px solid;
+        border-color: #aaa;
+        margin: 1em 0em;
+        padding: 1em;
+        page-break-inside: avoid;
+    }
+
+    /* Remove the blue background in the top left corner, around the logo */
+    .wy-side-nav-search {
+        background: inherit;
+    }
+
+}