A button to Undo or Redo 3 most recent changes

[CalliEve]

Keep the state from before the last changes as a queue of max 3 items.
If undo using button on canvas overlay, or ctlr+z, add current state to redo queue and set current state to state popped from the front of the undo queue.
If redo using button on canvas overlay, or ctlr+shift+z, add current state to undo queue and set current state to state popped from the front of the redo queue.