A new theme for the kitty website

Supports dark mode. Also re-organize the documentation
a bit, making it more hierarchical.

Have a nicer landing page

docs/_templates/base.html

@@ -0,0 +1,19 @@
+{% extends "!base.html" %}
+{% block extrahead %}
+  {{ super() }}
+  {%- if analytics_id %}
+      <script type="text/javascript">
+      var _gaq = _gaq || [];
+      _gaq.push(['_setAccount', '{{ analytics_id }}']);
+      _gaq.push(['_setDomainName', 'none']);
+      _gaq.push(['_setAllowLinker', true]);
+      _gaq.push(['_trackPageview']);
+
+      (function() {
+        var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
+        ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
+        var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
+      })();
+    </script>
+  {% endif -%}
+{% endblock %}