Nemo's Enchantments

# Changelog v1.9

## Changes
- Added the Head-Hunter enchantment
  - Available only as treasure loot found in chests
  - Supports melee weapons, bows, crossbows, tridents, and maces
  - Adds a 0.84%, 1.68%, or 2.52% chance to drop a supported mob or player head at levels I, II, and III
  - Excludes Wither Skeleton skulls, which retain their vanilla drop chance