Fix 6155: OpenGL2: some shader stages remains visible through fog volumes

Fix CalcFog in generic_vp.glsl to fog fogged surfaces.
Now it's the same as CalcFog in fogpass_vp.glsl.

Fixes shaders that use adjustColorsForFog. Impact wallmarks, blood sprites, flame textures and so on.
Fix a few warnings
map_developer cvar to show missing shaders
Merge branch 'master' of https://github.com/ioquake/ioq3