This untangles some of the gigantic kitchen sink headers
in an attempt to split things into smaller files.
Also don't include gl.h, glext.h, windows.h,
and other such nonsense *everywhere*.
Lots of cleanups on the way too. More dead/unused code removal.
Remove incrFlag(), decrFlag() Lua functions.
Continuity resets load a bunch of small files from disk;
this speeds up the startup precess very slightly if the files
are not in the OS's file cache yet.
