Would be nice to limit certain types of bedrock ores to certain biome types.

In addition to certain mods doing this, a good example is emerald in vanilla.

6254c33

Took that as an incentive to make the ore gen config JSONs a good bit more flexible: they can now do both dimension and biome constraints. Dimensions can be specified either by id or more generically their type (0 vs. overworld), biomes via their registry name or more generically their type (abyssalcraft:darklands vs. warm). And they can alternatively be set to be interpreted as a blacklist instead of a whitelist. See example JSON for the format. Using that for emeralds now and also for #32!