Also: Recently introduced key names in usersettings.xml will no longer work.
But this should automatically detect key names as they used to be,
and convert automatically. Needs testing.
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.
