Backport Ice Cave ore generation to Sulfur Caves

Ice Caves managed to nicely solve the problem of "if all the stone is replaced with other blocks, then there's nowhere for ore to spawn" by having it generate in small blobs of stone replacing the ice and calcite.

Currently, Sulfur Caves are pretty, but mostly a waste of time to go caving or mining in because ores have so few places to spawn; this could be fixed by letting ores generate there the same way as in Ice Caves, in the same small blobs of stone replacing sulfur and cinnabar.

Judging by how the Ice Caves turned out, this shouldn't compromise the visuals of the Sulfur Caves at all (if anything, they'd help break up the solid yellow *just a bit*), and it shouldn't make mining there too easy because you'd still have the cave spiders and toxic pools to worry about.