Switch to using BATTERY_STATUS for battery info

Fix video initialization - VideoReceiver did not start because sink was not created because videoBackgroundComponent was not loaded on startup if video was disabled

Allow developers (or advanced users) to override UI settings - quite useful if you set your debug settings in QtCreator and do not depends on QGC settings state (they are reset to default sometimes, for example)

Every single line of this function is commented out, and the
documentation of GStreamer says that it's uneeded.

CP - If GCS starts receiving its own coordinates, don't change the map center if it is already tracking the vehicle.