Add automatic generation of a todo item page

This adds a script to generate the todo item page from
bugzilla. This requires a valid username+password for
bugzilla, so it is intended that this only be run on
the libvirt.org website via cron. Normal usage will just
generate an empty stub page.

* docs/todo.pl: Script to extract todo items from bugzilla
* docs/todo.cfg-example: Example config file
* docs/sitemap.html.in: Add todo page
* docs/Makefile.am: Generation rules for todo items

docs/sitemap.html.in

@@ -275,6 +275,12 @@
       <li>
         <a href="bugs.html">Bug reports</a>
         <span>How and where to report bugs and request features</span>
+        <ul>
+          <li>
+            <a href="todo.html">Todo list</a>
+            <span>Main feature request list</span>
+          </li>
+        </ul>
       </li>
       <li>
         <a href="contact.html">Contact</a>