Left 4 Dead 2 - Update

- Enable controller navigation of menus to support Big Picture mode.
- Allow client menus to execute restricted client commands.
- Fixed special infected not catching fire if they were already burning from incendiary ammo.
- Hunter and Jockey won't be killed if slashed mid-leap by another infected.
- Infected damage applied to a Jockey rider is ignored for the Jockey and no longer passed on to the Survivor. This fixes Jockey victims being subject to double damage from infected attacks and instant incap from Tanks.
- Tweaked boss zombie spawn timing in Versus to prevent the Tank spawning as soon as the Survivors exit the safe room.
- Fixed the first maps in Dead Center and Swamp Fever not using the boss spawning rules for starting maps, which are more restrictive than other maps.