Do not delete atoms that have a label - when they still have bonds

Signed-off-by: Lennard Wasserthal <Wasserthal@nefkom.net>
Restore undoes also when already work-in-progress-undone

If the undo is restored during work in progress, it is intended to
become dirty WITHOUT another storeundo.

Signed-off-by: Lennard Wasserthal <Wasserthal@nefkom.net>