Increase compatibility with BountyHunters plugin

[crashdemons]

Duplicate heads are dropped despite settings to avoid this (when player drops and BH head drops are both enabled).

This issue can be avoided by disabling player-head drops on one of the two plugins, currently.

Recent changes do not affect this as it's assumed the BH plugin is intercepting the death event early, which puts this plugin in the sticky situation of changing its priority to be able to intercept it first - and last, which is not the best idea in design.