App messages now use simple modal message dialogs. Vehicle messages continue to use non-modal popup.

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

- GeoFence support comes from plugin
- Circle fence support
- Better param support

Instead us a Toolbox concept which hangs off of QGCApplication

- 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