GearBlocks Demo 0.7.8420 — GearBlocks Steam update #978404

Hi all, over the holiday period I decided to take some time out to try an experiment: attempt to add undo functionality to the game. Specifically, implement a command history, to which a command would be added for each tool action (e.g. select, move, or attach parts, apply material or paint, etc.) and then allow the player to undo or redo the commands in that history. The game's tools were not originally built with this in mind, but the code is reasonably well structured so I thought it might be possible. The initial prototype turned out to be promising, and showed the potential improvement to usability this would bring. Well, I couldn't resist seeing this through to completion, and so that's what I've been working on for the past few weeks. It required substantial refactoring of some of the tool code, and took a wh...