Fix memory leaks in KisMergeLabeledLayersCommand
Before this commit, KisMergeLabeledLayersCommand would keep the image and paint device for as long as it is kept in the undo stack. It's not needed, because the undo uses different ways to determine how to undo and redo the selection. After this commit at the end of the merge the command will clear its shared pointer, which will in turn ensure that those objects will be removed when nothing else will be using them.
Showing with 17 additions and 2 deletions