Mavlink terrain protocol support

Only check latest stable firmware one time

Fix placement of _sendNextQueuedMavCommand

Remove BatteryFactGroup::cellCount support

Handle unreliable PX4 support of BATTERY_STATUS

Switch to using BATTERY_STATUS for battery info

This was lost when moving the handling the the trajectory points from within the vehicle.

Allow plugin to add flight modes to joystick button actions

Remove qDebug

Fix distance sensor telemetry reading

64 bit fixes

ADSB server support provided through new ADSBVehicleManager implemenation

Treat VHR_HUD.throttle as int16 for reverse throttle

Fix flight timer

Better flight trajectory point algorithm

Plugin'ized follow me support

Enable ArduPilot motor testing

Fix/update offline vehicle capability bits and mavlink version

Configurable Go To Location max distance

- Add setting for Heading to Next WP and Nort Up lock
- Add check for vehicle for every indicator to avoid showig them while
  no vehicle

Bump GoTo limit to 10K.

Support up to 64 buttons, not limit to 16
Send a single button command and not a stream of commands at 25Hz
Send button commands through signals (it's coming from a different thread)
Hide gimbal support through analog channels (there are no MAVLink messages to handle it)

Map gimbal controls
Keep track of gimbal position within Vehicle