Thwomps now squish the player - might need to reduce player height to 1 or something temporarily

Mushrooms rewritten to not use Instathrust, instead they jack up your accel to 10x. Feels nicer.
Floor mushroom panels no longer activate while above them
Mushrooms force player to accelerate (and cannot brake)
K_PlayTauntSound works now. (YES YES YES HUP HUP YES HUP HERE WE GO)
Star and Mega sfx might stop correctly now in netgames (need to test)
Item box radius and height increased from 32 to 36.