Instead us a Toolbox concept which hangs off of QGCApplication

Plus lots of other tweaks to ui for visuals

This fixes rotate images showing up at the wrong time

- select active vehicle
- arm/disarm
- select flight mode

- New MissionManager
- Plumb MissionManager through MissionEditor
- Mission Editor supports get/set

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

- FirmwarePlugin is the new place for code which is specific to
firmware flight stack
- FirmwarePlugin currently supports flight mode apis
- Modify code to use new FirmwarePlugin support