* Add 3DR Solo, Parrot Discovery video sources

* New solo video handshake, remove stale code

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.

Make ToolStrip font smaller (Desktop builds)
Check for auto configured video stream before testing video source type

Object ownership handled by SettingsGroup base class

Updated MAVLink to handle video stream types (auto discovery)

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

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