MSAA was a long wanted and often requested feature. Just set set the
desired number of samples with gl_msaa_samples and do a vid_restart.
This code is based upon work done in Hecatomb.
Those extensions have become part of ARB about 15 years ago and most if
not all video cards still in use should support the ARB versions. I
believe that at least parts of this code were disfunctional.
This removes the need to define the old qgl function names to the
official OpenGL names. The OpenGL functions are now called directly
without any abstraction.
