1) Added compatibility with java 16
2) No longer map chests to enderchests for < 1.13 (this will make chests close to each-other not render, but that is preferable to not being able to break them)
3) Fix translatable components translation not translating extra components
4) Improve legacy potion mapping (now uses specific bits to parse type and properties instead of hardcoded ids)
5) Support custom biomes mapping (uses first legacy mapping if manual mapping doesn't exist)
6) Fix varlong read