Better attempt at adding Apple meta key
Change node can set msg property to another msg property. Closes #456
Merge pull request #457 from anna2130/change-node-multi-level-properties

Change node can set msg property to another msg property. Closes #456
Add node input labels for subflow
Subflow stuff

This commit will get squashed before merging to master
Make subflows draggable and editable
Add subflow history support
Add create subflow menu option
Update palette labels for overly long labels
Update menu options when tab/flow renamed
Add subflow delete to history
Add undo history for create Subflow
Add instance count to subflow dialog
Add subflow icon
Add individual subflow node edit dialog
Add edit subflow button to workspace
Add better 'instance in use' message to subflow
Add runtime support for subflows
Prevent circular subflow references
Update sidebar info pane for subflows