User can undo actions in labeling page

[juliapacula]

Current Behaviour

• when you click on a label by a mistake and delete it, user is not able to undo the action
• when user labels something by a mistake he has to delete the label (first - he has to find it)

Expected Behaviour

• as a user I would like to have a permanent button (may be located in panel "actions") so a can undo and redo actions (by actions I mean: deleting label, pinning label, marking anything on a scan)
• great feature would be key shortcuts for those actions (ctrl + z for undo, ctrl + y/ ctrl + shift + z for redo)