[FEATURE REQUEST] Buttons or shortcut for undo/redo

[MarxismeetChill]

The title says it all, but it would be nice to have a feature to undo and/or redo a brush stroke, for example. I hope that makes sense? A feature "undo and redo" xD

[jackcummings]

Dude... if all of the things to leave out, why would you leave out undo/redo????

But seriously though, I spent like an hour excluding different parts of a mesh because the angle detection for fill doesn't work very well, then I hit one wrong button, all gone