[FEAT] Hotkey to flip Alt-key-behaviour

[dthv]

The Alt-key is great: It inverses the snapping behaviour of so many things. But there are occasions that you want to quickly change which one (to snap, or not to snap! :skull: ) is the default.

I would like to propose adding a hotkey that affects the settings on whether things snap by default (and won't snap with Alt pressed) or won't snap by default (and will with Alt pressed).

This could e.g. be Shift+Alt or Ctrl+Alt. Alt+Tab would be very consistent with the Tab behaviour in PA, but would probably be a nuisance for many users… ;)