The previous approach was to have a world generate with vanilla biomes and then use it as a template for the seed world. This PR replaces that with a comprehensive vanilla biome generator using details from https://minecraft.wiki/w/World_generation. There are some tweaks to make the cave biomes more likely:
The deep dark is not required to be so deep.
The humidity requirements for lush caves are lower.
The previous approach was to have a world generate with vanilla biomes and then use it as a template for the seed world. This PR replaces that with a comprehensive vanilla biome generator using details from https://minecraft.wiki/w/World_generation. There are some tweaks to make the cave biomes more likely: