Using terrain layers to change the simulation behaviour

[alin256]

One cool idea for procedural terrain generation would be different geologic layers that affect the steering bias. So when you're in a "hard" layer, maybe it doesn't turn as sharply (and so on). It could be a color lookup like the collision detection.

Originally posted by @gradyh in https://github.com/CodingTrain/Directional-Boring/issues/2#issuecomment-1172479254