fix(selection): do not select connections
fix(selection): do not select connections

This restores the old behavior (only shapes can be selected) until we
are able to properly select connections, too.

Related to #57

tsneed290/diagram-js,tsneed290/diagram-js,bpmn-io/diagram-js,thr0w/diagram-js,thr0w/diagram-js,pedesen/diagram-js,pedesen/diagram-js,chudaol/diagram-js