Support both relative and absolute FOLL_ALT_TYPE

Bringing preflight checklist to mainline QGC

Remove unnecessary pointer check before delete 

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

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

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

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

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

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

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

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

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

Switch from builtin video sink to qmlglsink (v2)

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 gstreamer debug settings

Checklist enforcing

Remove unused function

Fix Done in Toolbar when switching to Plan View

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)

Code documentation and updates