Moved #defines

Moves the constants from defines and compile_options files into the __DEFINES directory.  The compile options in the latter file that are actually tweakable remain in their existing file in the code directory.
Constants from DEFINES.dm, globals.dm, names.dm, and global_lists.dm have been moved into the _globalvars subdirectory.
stylesheet.dm has been moved into the interface directory since that's a better place for it.

This move contains no code changes for stock TG.  It is purely an organizational move.
Some global constants that appear to be unused have been put into unused.dm, but not unticked.  This list is by no means exhaustive.

Branches should be aware that they need to move any additional defines and global constants manually.