Feature Request: Set order of stone types for strata layers.

[ColossalRenders]

The ability to specify which stone types generate higher and which ones lower when using the strata layers feature would be really useful for modpacks. For example, if a mod adds multiple stone types with different hardness/mining levels, they can specify "weaker" stone types to generate on top of "stronger" stone types, improving mining progression. Even better if the order can be set per-biome.