Fix broken r_fencesync
Wrap GLimp_EndFrame with R_EndFrame

There is no need to have high-level OpenGL functionality in a platform
specific implementation file
Move antialiasing support out of VR code path
-AA modes are now applied across the entire game, not only to VR modes
-Deprecated vr_antialias in favor of r_antialias
-Remove menus for vr_antialias
-Replace non-power-of-two option in the video menu with antialiasing option
Bug fixes for Rift support
-Temp fix for incorrect pixel scaling
-Fixed incorrect verbage for the bspline bilinear options
Make OVR latency test work if distortion is disabled
Simplify vsync options
Merged vr_hud_bounce_mode into vr_hud_bounce