Extend a time-delay nerf option to all mobs

[crashdemons]

Requested feature to nerf farming (including gold farms):
use a nerf similar to the player death spam nerf option to prevent head drops for mobs when the same mob is killed within a minute (or configured time).

note: unlike player death spam nerf this should not reset when someone repeats the "spam", that is a spam of mob kills will still drop once a minute regardless of delays or lack of delays.
A spam of player deaths by contrast will not drop until a 1 minute delay is taken in order to incentivize players not to spam chat.