MLHR-1445 # resolve
* Stub out operator attributes
* Show and store operator attributes in DAG editor
* Add "display_name" property to operator and port attributes and use that
Do not put attribs in each operator, just render from the global list; Remove unnecessary clone() calls from properties and attributes.
Merge pull request #222 from zack-dt/port_oper_attribs.MLHR-1445

MLHR-1445 # resolve