Command Destructors #44
Description
None of the command related destructors are implemented yet, and there's plenty of commands that will leak memory.
Command invoker should be responsible for deleting invalid commands (i.e. ones that don't make it to the undo() list because they didn't change anything) and cleared commands (i.e. ones that get cleared from a redo stack if a new command is run after undoing a bunch).
Some commands so far (most notably detach() ) will definitely leak memory if deleted. We should go over the commands one by one and verify that everything is properly cleaned up.