it works?

probably a bug riddled mess that will crash your server...Alpha
new Gamerules control behavior:

mobCapMonsters = MONSTERS group mobcap. includes hostile mobs.
mobCapCreatures = CREATURES group mobcap. includes passives like sheep and cows.
mobCapAmbient = bats
mobCapAquaticCreature = Squid
mobCapAquaticAmbient = Fish
mobCapPerPlayer = controls whether mob caps are calculated per player or per server