Related to bpmn-io/diagram-js#107
BREAKING CHANGE:
* Modeling#moveShapes got renamed to Modeling#moveElements
* Id of command changed from 'shapes.move' to 'elements.move'
It is now possible to add bendpoints to flows or drag bendpoints to
update their position / trigger reconnects.
Upon bendpoint move a rule is checked to figure out whether or not a
bendpoint operation is allowed or not.
Closes#123Closes#138Closes#139Closes#165