Loot overwrites, more options

* Loot lists can overwrite global settings (e.g. refill delay, stack
amount).
* Chat and entity spawning modifications can be disabled completely to
improve integration into existing plugin environments.
* Grenade damage can be disabled/enabled for players and zombies
separately.
* Wood harvesting can be disabled. NOTE: Not used yet anyways.
Fireplaces are a plan for the future.