undo / redo, unselect
added features:
- moves can now be undone
- selected tiles will be ignored during undo
- the undo option can be found in the GUI under 'edit'
- undone moves can now be redone
- selected tiles will be ignored during redo
- the redo option can be found in the GUI under 'edit'
- selected pieces can now be unselected by performing an action on them
bugs:
- fixed an issue where goat player hasn't been able to win matches
- fixed an issue where the selected pece stays selected after a goat player's move