Avoiding (pathfinding around) certain blocks

[fatboychummy]

In some modded instances, the turtle is unable to mine more blocks than just bedrock. Because of this, the turtle can get stuck underground. We can currently exclude these blocks, but the turtle will not actively avoid them.

I would like to avoid adding a pathfinding algorithm into this project, as it'll be a fair amount of extra code and complexity for very little usage. I can probably add it in such a way that it won't actively effect anything unless you include the avoid flag, but at this moment I'm unsure how much it's even needed.

If there's enough support I will definitely look into adding this, but for now I will wait.