This severely reduces the calles to BindTexture, and more importantly,
glUseProgram, EnableVertexAttribArray etc. The biggest changes are:
o icons and text are all in the one giant texture
o icons and text are mixed in the one queue
This gave ~9% speedup for bigass1 (159->174fps).
It doesn't seem to have any useful effect in QF (even before the plugin
project) other than setting the number of frames to update. I'm not sure if
it's a useless variable or one where the user is supposed to match it to
the system configuration. Anyway, with this, the glsl plugin now works.
The renderer should now be free of any direct access to client code. Even
3d rendering is now done via a function pointer.
The cshift code is done as a 2d screen function.
Add GLSL directory to QF and use it for all gsls based code (instead of
GL). defines.h, types.h and funcs.h are derived from gl2.h from khronos.
Text drawing now uses triangles instead of quads.
