MADE A MISTAKE WITH THE MARBLE? NO WORRIES, NOW YOU CAN REWIND TIME WITH THE SUPERPOWERS OF THE HISTORY

JUST USE THE UNDO/REDO BUTTONS AS YOU WOULD EXPECT IN EVERY SOFTWARE EVERYWHERE (and I would like this ability in life please)

making it work was not so obvious tho - so I decided it was important to implement it first before doing more COOL stuff

going forward, every action should know how to undo/redo itself

next up: colors!!! (and some more visually pleasing tiles)