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

Too complicated supporting both modes as editor becomes more complex

These use OpenGL implementation which prevented moving to ANGLE
support. Since they are rarely used they are being remove instead of
being upgrade.

These use OpenGL implementation which prevented moving to ANGLE
support. Since they are rarely used they are being remove instead of
being upgrade.

Plus lots of other cleanup

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

Sorting source and headers while at it.

Moved update canvas signal to perspective load instead of hooking it to the paint event.
Added an "S" as the unit for the number of cells fact (as in 4S).