Added a big todo list, you can make suggestions if you want.
I want to revisit the cobblestone bedrock and gravel, I'm not happy with any of them, they're all too noist and gravel/bedrock is impossible to distinguish in the darkness. If anyone particularly wants me to keep them then they should say so and in future updates I'll pack them as terrain_oldcobble for you to use if you want to.
On the alternatives note, there are already three varieties of cow, just swap out the files if you want a browner cow or a blacker/whiter cow.