Allow applying a procedure just once, at the start or end

[kamilburda]

This should be relatively easily doable as the code already internally uses several action groups - actions that are performed once at the start, once for each item (layer) and once at the end. The action group should be modifiable for each procedure separately - in the action edit dialog, this should be placed under More options.

[kamilburda]

Closing this as I failed to identify good use cases for this feature. One such case could be changing the active brush, gradient, ..., but that can be done for each item without any performance penalty anyway.