We want to be able to use unpacked MPQs on low-end platforms
(PS2/rg99/etc).
This is tricky on case-sensitive filesystems. Avoids case issues by
lowercasing all paths in the code (then we'll just need lowercased
listfiles).
- Add file documentation to about 1/4 of the files in Source
- Copy over a lot of the documentation from the sanctuary/notes repo
- Standardise all the existing documentation
- Create a configuration for Doxygen
- Add more documentation (engine.cpp is now fully documented)