More depth specific caves

The Caves and Cliffs added some really cool new cave biomes, but I think the underground needs more. And a neat way to implement these new caves is to make depth specific biomes. Having depth specific biomes narrows the search when looking for these biomes. I also think it gives character to the biomes. Instead of finding them anywhere, you have to travel to a certain layer to find them. It may just be me but that makes them more interesting.