Added packages to facilitate division of labor
Further refinement and fleshing out of drag and drop interface.  This
commit includes item selection on the stage, auto-connect from last
item's output to newest item's input (for testing only and will be
removed), movement of selected item on the stage via keyboard,
publishing of custom events from items on the stage to facilitate moving
with control at the StagePanel level
Began establishing framework for execution engine.
Pushed additional changed files for execution engine framework changes.