OpenGL2: Add fourth cascade for sun shadows, and adjust sun shadow cvar defaults.
OpenGL2: Remove R_MipMap() and R_MipMap2(), and fix gamma conversion in R_MipMapsRGB()
OpenGL2: Fix a glsl compile error on old hardware with r_shadowFilter 0.
Merge branch 'master' of https://github.com/ioquake/ioq3
Merge branch 'master' into ProxyClient