Fix hunter job payouts not being applied

[DersWasTaken]

Entities that die after being hit due to non-player means such as fire aspect, cactus, or magma blocks, don't give player payouts.

To fix this, a cache entityLastDamager was created which tracks the last damager of the entity, and is used to set the killer of the entity (Entity#setKiller) when the last damage cause on entity death was not another entity.

[DersWasTaken]

I didn't add a config option for this because I don't think its necessary. There isn't a way to exploit this that doesn't require you to hit the mob atleast once, and the minimum damage amount config option still applies. This can be added if needed to get the merge approved.