Move procedurally generated surfaces to cgame

Sprites are currently still generated in renderers.
Beam doesn't work quite the same (need a custom shader), but nothing uses it.
Move renderer rail cvars to cgame
Increase max poly verts and decrease max poly buffers

Need more poly verts for RT_POLY entities.
cgame only tries to use 128 poly buffers, 600*4 is over kill. Especially since they don't even work right now.