Use Google Custom Search API for searching in docs

doc/utils/sphinx-config/_themes/lammps_theme/search.html

@@ -1,50 +1,20 @@
-{#
-    basic/search.html
-    ~~~~~~~~~~~~~~~~~
-
-    Template for the search page.
-
-    :copyright: Copyright 2007-2013 by the Sphinx team, see AUTHORS.
-    :license: BSD, see LICENSE for details.
-#}
 {%- extends "layout.html" %}
 {% set title = _('Search') %}
-{% set script_files = script_files + ['_static/searchtools.js'] %}
 {% block footer %}
-  <script type="text/javascript">
-    jQuery(function() { Search.loadIndex("{{ pathto('searchindex.js', 1) }}"); });
-  </script>
-  {# this is used when loading the search index using $.ajax fails,
-     such as on Chrome for documents on localhost #}
-  <script type="text/javascript" id="searchindexloader"></script>
-  {{ super() }}
 {% endblock %}
 {% block body %}
-  <noscript>
-  <div id="fallback" class="admonition warning">
-    <p class="last">
-      {% trans %}Please activate JavaScript to enable the search
-      functionality.{% endtrans %}
-    </p>
-  </div>
-  </noscript>
-
-  {% if search_performed %}
-    <h2>{{ _('Search Results') }}</h2>
-    {% if not search_results %}
-      <p>{{ _('Your search did not match any documents. Please make sure that all words are spelled correctly and that you\'ve selected enough categories.') }}</p>
-    {% endif %}
-  {% endif %}
   <div id="search-results">
-  {% if search_results %}
-    <ul>
-    {% for href, caption, context in search_results %}
-      <li>
-        <a href="{{ pathto(item.href) }}">{{ caption }}</a>
-        <p class="context">{{ context|e }}</p>
-      </li>
-    {% endfor %}
-    </ul>
-  {% endif %}
+<script>
+  (function() {
+    var cx = '012685039201307511604:um7if1hinba';
+    var gcse = document.createElement('script');
+    gcse.type = 'text/javascript';
+    gcse.async = true;
+    gcse.src = 'https://cse.google.com/cse.js?cx=' + cx;
+    var s = document.getElementsByTagName('script')[0];
+    s.parentNode.insertBefore(gcse, s);
+  })();
+</script>
+<gcse:searchresults-only></gcse:searchresults-only>
   </div>
 {% endblock %}