Re-enable zombie mutations

[ViolentViolet]

The mutations screecher and sniffer were working fine.

Zombies are less mobile than players and have to wait for players, chasing them across the map is not really an option.
Getting shot is a fast death, the playing field could be leveled a bit since it takes a lot of bites to damage someone. And last I check punching did only damages NPC's.

[shalls]

I agree. There isn't much incentive to be a player zombie currently. Player zombies should be given the privilege of being more physically and genetically advanced than the usual NPC bots.

[Awide]

Enabled.