Branch/blockly viz

This branch should be tested with vwf branch/blockly which also has a pull request.  The 'toggleBlocklyUi' event has been removed and replaced by blocklyVisibleChanged' event.  The application has a top level property 'blocklyUiNodeID' which controls what node is being addressed by blockly.  To hide blockly, send in the same id or possibly undefined.

Question:  should blockly be visible at startup?  Currently the blockly interface is hidden on start up, which maybe wrong.