Despawn Tweaks

Multiloader port of DespawnTweaker, a performance mod that fixes cases where mobs won't be removed.

Features: - Allows mobs that pick up items or gear to despawn naturally. - Drops held loot properly when mobs despawn. - Allows mobs that spawn from spawners to bypass this rule, optionally only in specific structures. - Improves performance on both dedicated servers and in singleplayer.