chore(modeling): cleanup + tests for connection parent change
feat(rules): distinguish not allowed / ignore

Related to #55
feat(move): visually drag multiple shapes
feat(modeling): move enclosed connection with shapes

This commit enhances the MoveShapesHandler to move enclosed connections,
too.
feat(command): invoke post-execute listeners after command

This commit swaps the execution of post execute listeners.
They are now executed as the final step (after the commands own
postExecute handler) and may perform additional actions after the
default actions have been carried out.