Undo buffer #94
Description
TODO: implement an undo buffer. This is kind of important as python commands can really trash a world if you get them wrong.
My idea is this. Before any update to the world, clone the effected region into a safe haven at some distant point in the map.
- support multiple undos
- Stretch goal: devise a way to save the index into the undo locations in a block somewhere. That way undo will still work after exit and re-entering the world