Updated MAVLink to handle video stream types (auto discovery)

On desktop (Ethernet connection), the ground unit pushes UDP directly, which makes the use of an actual "Link" not possible. Instead, I've moved all of Taisync support to a "manager" owned by QGCToolbox.
Added a Taisync settings with some basics already wired and running.

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

Ignore Fact index if there are no enums (avoid adding an "Unknown" entry)
Add function to convert and clamp a (Fact) value.

Remove/comment off debug output pollution

- 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

Calling delete on a socket callback is not safe and this can crash
QGroundControl. Using deleteLater method from socket to perfom deletion.