MAVLink decoder: Run at lowest priority

Stable merge

Rework vehicle sensors_health alert

Better handling of resume mission upload failures

Internet availability test fixes

Fix for missing altitude updates on APM

Internet Test

Handle joysticks with duplicate names

Add joystick button limit

Switch test from 8.8.8.8:53 to "www.github.com:80"

Radio upgrade: Point updater to a binary which is fully MAVLink 2.0 enabled, including radio status.

This is important to avoid having QGC hijack links that are active (we read 2000 bytes!) but are definitely not MAVLink. This can have nasty side-effects, e.g. if we would talk to an LTE modem in a laptop or alike.

Switch only to MAVLink 2 on first connected link. Fall back to v1 if two links to the same vehicle are connected and one can only do v1

This extension introduces a complete version handshake mechanism which will detect wether the vehicle AND the complete link / routing infrastructure support MAVLink 2. If they do, QGC will switch to the highest protocol version supported by all connected vehicles. If a new vehicle connects, it will re-negotiate the highest possible version. This means that we error on the side of compatibility, which later can be easily changed.

Add TCP-Mpeg2TS support to available video feeds

Make recording status more obvious

Mission upload: Extra paranoia around write index list

Plan: Terrain display in MissionItemStatus

Add gps coordinates to vehicle gps factgroup

Stable -> master

Mission/Survey related fixes