We'll use this to index some things in our own search engine without
exposing it to external sitemap parsers. Not from a security standpoint
of course, but something that will lead to it being possible to search
the devel docs again.
Each module now contains a struct.py file that will return all
the URLs that it can generate (yes, this is a small break of the
abstraction of url.py, but we've broken that elsewhere as well),
and also which search-engine-weight (0.1-1.0) that this URL should
be given.
