Instead us a Toolbox concept which hangs off of QGCApplication

This is in preparation for full Qml main window

Too complicated supporting both modes as editor becomes more complex

- MultiVehicleManager is a Qml friendly replacement for UASManager
- Vehicle is a replacement for both UAS and AutoPilotPlugin

If Facts are referenced from FactPanelController, we need to reference
count the AutoPilotPlugin such that it doesn’t get destroyed until
after the FactPanelController is destroyed.

{ } generates an empty object