Initial support for loading "proto big cube" converted 1.12.2 CC worlds#681

Niko-sk2x wants to merge 1 commit intoMC_1.17OpenCubicChunks/CubicChunks:MC_1.17from

MC_1.17_loadOldWorldsOpenCubicChunks/CubicChunks:MC_1.17_loadOldWorldsCopy head branch name to clipboard