Move cache location methods so they are available in all builds

Add missing header

Add --clear-cache option

Fix typo

Add support for specifying fixed RTK base position

Change to case insensitive compare

Move ArduPilot preflight check handling to generic QGC

Fix mobile builds

Stable desktop version check

Remove unused code

Show the link indicator in the tool bar if two or more links are connected and at least one of them is a high latency link.
Show in the link indicator if a link is inactive.

Make all argument to AirMap queries based on what the screen shows (bounding rectangle and/or radius), respecting the limits imposed by AirMap.

Break apart string of classes into their own files as all in one file became unwieldy
Expose Airspace data in a QML ready format
Split global Airspace from AirMap (Only now I figured out the reason for the pure virtual root classes)
Refactored a bunch of things to make it consistent and/or obvious

Move all airmap related stuff to its own directory