[MP] Match SDL sound with s_khz default.
[SP] Match SDL sound with s_khz default.
[MP] Cleanup else and endif blocks in main cmake script.
The requirement for how we were doing this in some blocks is much older than the version we require.
[MP] Rend2: Allow parallax on non-map surfaces

Parallax mapping was previously disabled on entities, as well as stages
marked with lightingDiffuse/lightingDiffuseEntity. This commit removes
this restriction.
Merge branch 'master' into rend2