Add a save button to the paint mode#337

It would be nice to be able to more easily manually save paint jobs, in case of crashes and the like. Having to move off of your paint job in order to save it feels clunky and reduces the frequency users are willing to save their work.

I know there is an autosave and I can save by changing schemes but a manual save button (with confirmation popup still) would put my mind at ease.

Optionally a %s to save with feedback! Even though it’s probably already autosaved