They have been separated into low-level stuff that you wouldn't really want to ever edit (like the definition of PI) which are in __DEFINES.dm
The others, which hosts could possibly want to modify for their server, are located in _compile_options.dm
I've tried to group it together in some sort of logical way so it's easier to find what you need. Feel free to move whatever.
Main reason for the change is so we can add some more compile options into the game to make it more configurable.
git-svn-id: http://tgstation13.googlecode.com/svn/trunk@5825 316c924e-a436-60f5-8080-3fe189b3f50e
