This reverts commit 6620f803.

Previously, a completed file upload lead to this assert:
    Q_ASSERT(!_ackTimer.isActive());
because _closeUploadSeesion() was called twice, thus activating the timer
twice.

ADS-B vehicle timeout and stacked callsign

Linux: Add missing lib

Flight display: Add callsign to transponders

Linux: Add missing lib

Better display of vehicle indicators for multi-vehicle

Add support for ADSB vehicle display

More support in multi-vehicle view

Plus other ui tweaks

Stable merge

GeoFenceManager: Add missing signals

FactSliderPanel.qml: Correct brackets position

Give access to mavlink message stream to core plugin

Stable merge

Update for ArduCopter 3.5 release

Stable merge

Allow custom overrides of windows installer icons