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