See description for full changes

Added zombie director (spawns zombies) and merged with tick handler.
Removed zombie claws (for now).
Removed pain particles and sounds from zombies (hacky, need to overhaul
damage system later on for decreased friendly fire damage regardless).
Added random skin colors to zombies and prevented missing pants.
Fixed console spam from ::directZombieMovement.
Fixed accidental range limit on zombies and made distance retargeting
more allowing.
Fixed direct movement checking.
Added damage to survivor shoving.