Re-posted, due to inadvertent deletion

Changes

• Add ProtocolLib to soft dependences.
• All 1.15 biomes are now included in the default biomemaps. While they are not required -- biomes not found are mapped to themselves -- it is easier to understand and edit the complete list.
• Due to a vanilla MC feature, ocean biomes are remapped to FROZEN_RIVER in the default snowbound biomemap, instead of FROZEN_OCEAN and DEEP_FROZEN_OCEAN. The new mapping produces snow everywhere.

This version supports only Spigot 1.15.2.