Epic Terrain Compatible

It's a beta version! I can't guarantee that updating the world to the beta or exiting the beta will be 100% safe. Make a backup!

Contents:

• Based on the new bottom layer written by vanilla, reset to the whole.
• A new river system with large rivers and small rivers, with a drop function, and a source.
• Epic Terrain New simulated erosion algorithm in experiments.
• Improved compatibility with most major biomes,Such as Terralith, wwoo, Oh The Biomes We've Gone, Biomes O' Plenty.