Update Zombie Pigmen AI

In comparison to the new AI of Villagers, Zombie Pigmen are quite archaic, especially in multiplayer. The fact that a single individual can anger every single Pigman in the Nether, essentially disabling it for some in-game days for other players, is ludicrous.

I propose a player-by-player reputation system. One that keeps Pigmen angered at specific players, and continues to ignore others unless provoked.

If not that, at least make it so that if they successfully kill or cause the death of the one who angered them, they'd calm down.