* Some of our chapters are pretty long and this should make it much
easier for a user to find what they're looking for and jumping
to it. It's easier to read the section toc at the top of the
chapter, than it is to read it in the sidebar.
* added a YouCanHelp directive to replace FIXMEs and encourage contributors
to help out
* moved some bits around between the hacking howto and the codebase documents
* expanded on the stub nature of the theming howto
* tweaked some other text
