The VideoReceiver should work 'as is', without depending on the
whole application or in the settings. This patch removes all the
hard dependencies on QGroundControl, FactSystem and Settings system
so it's easier to isolate and test the code.

Disable video workaround for gstreamer crashes

Updated MAVLink to handle video stream types (auto discovery)

Moved "Grid Lines" out of General Options and into the Video Stream Widget
Made a QGC custom Switch element

- Added menu options to select new mode as well as new settings and defaults

Adding mux GStreamer plugin libraries to Android (to enable video recording on Android)
Adding an option to limit the amount to disk used for saving videos
Adding an option to show/hide the REC button (allowing plugins to handle the recording in their own way)
Adding simple frame grab to file

Also turn on MavlinkLogTest

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

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

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

Used for unit testing