Automatically unload mission if out of range and auto loaded

[MrD-RC]

Current Behavior

If you have set iNav to auto load missions, if the start point is too far away you can't arm.

Desired Behavior

Unload the mission and show a system message stating that the mission could not be used as out of range.

[MrD-RC]

Just realised, this may not be possible as there may not be a home position when the mission is loaded.