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

- 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.

QGCUASParamManager and friends are replaced by FactSystem

More consistent with Qml usage pattern

Passing parameters QVariantMap across C++ boundary was causing crashes
in Qt due to Qml array bugs. Referencing same Fact* across Qml boundary
in multiple QQuickWidgets caused jScript GC to crash.

Also, uas is kept in object

- properties now hand off of main “autopilot” object in qml
- Added support for summary items through qml

This way you don’t need to know parameter set ahead of time.

Plus a large number of other changes to allow for orderly shutdown of
objects without crashes or asserts. This is need for unit tests to
create/delete global state around every test.

Allows parameter access from QML among other things