[MP] Fix a copy-paste error in CG_TriggerAnimSounds.
[MP] Fixed a couple of Array compared to NULLs in CG_Player.
[MP] Fixed potential early null deref in AnimalNPC (accessing rider before checking not-null)
[MP] Removing a strange null check in PM_pitch_roll_for_slope that had no effect.
[MP] Ensure some data for world and none are filled out in the entity structure.
[MP] Removed unused prototype from G2_API.cpp
[MP] Fix SDL video driver checks.