Removed cvars:
* r_allowExtensions (always use extensions if available)
* r_allowSoftwareGL
* r_colorbits (use desktop color depth)
* r_displayRefresh
* r_dlightBacks
* r_ext_multitexture (required)
* r_finish
* r_ignore
* r_ignoreFastPath
* r_maskMinidriver
* r_measureOverdraw
* r_primitives (always use qglDrawElements)