Enable MSAA in OpenGL

[crashuxx]

This enables the MSAA in the OpenGL renderer.
"Antialias A tested object" need to be disabled in game settings

for some reason there's no aa in object that collide with sky , but that can be addressed later

needs more testing and cleanup, but the core functionality is here

[crashuxx]

I'm happy with the result I have here, there are still some rabbit holes that can be chased, I marked them with TODO for later

Tested with CS data on Linux AMD

[argosurvivors]

There is too much light and too much reflection on the ground plane on both examples, much more than in the original. Is it possible to adapt that in the next update?