LinkInterface/LinkConfiguration now reference counter using QSharedPointer

Even though it hasn't been supported forever, the files where still
being compiled

Prevent shutdown ordering crashes

PX4 doesn't retry commands by default

Change priority of messages from which altitude comes from

Also changed GPS FactGroup values to use NaN appropriately to show
unavailable values.

Don't show dynamic links in Comm Links

Turn off command retry logic for PX4 Stack

No need to add dynamic MockLink comm links

Change airplane compass icon to generic arrow icon

Null pointer issue

the message handleAltitude

altitudeAMSL and altitudeRelative do not need divide 1000，the unit is meter and float format。 can you use _handleGlobalPositionInt message for altitudeAMSL and altitudeRelative？ because _handleGlobalPositionInt is default 5Hz and _handleAltitude is 1Hz.

Change battery.current to float with 2 decimal places

Fix most (all?) QML font rendering glitches on Windows

Handling proxies when fetching tiles.

Charting Tweaks

MAVLinkLogManager: disable automatic start of log streaming

It's not desired to have automatic log streaming for several reasons:
- There's already SD logging (which is the case for the majority of the
  users)
- The link does not provide the necessary bandwidth (eg. wireless telemetry)

Updated MAVLink logging to the new “flightreport" form upload.

Vehicle::sendMavCommand Incorrect setSingleShot

Correct message handling: GPS_RAW_INT, GLOBAL_POSITION_INT, VFR_HUD, ALTITUDE

* Some code moved to Vehicle