By optionally passing the request object to Page.get_sitemap_urls() it
will now use the cached site root on the request object instead of
retrieving it for each call. This cuts the number of queries required
for a sitemap roughly in half.
All `.. code::` instances have been changed to use `.. code-block::`,
and have been properly formatted. The syntax names have been normalised,
so all django templates use the `html+django` syntax, shell commands use
`sh`, and plain text uses `text`.
