Hack fix for multi-vehicle disconnect on same link

Add GStreamer to OS X builds

* qmake silent build

* Disable silent build on windows

-closes #2913

This reverts commit 73d477cf.

Replacing the QGC icon throughout the application.

Radio cal scroll

Sensors: Use standard font size to fit on tablet

New QGC Logo

Fix null _activeVehicle references

Mission item fixes

Radio Cal: Only set reverse for multi-rotor

Fix references to __qgcPal which did not exist in control

Only accept numbers in FactTextEdit

Found a unused class, safe to remove.

All facts are numeric, atm. this means that the input should only
accept numbers. it already had the     inputMethodHints:   Qt.ImhFormattedNumbersOnly
option, but for some reason it still accepted letters and symbols.
by adding a     validator: DoubleValidator {} we limit the characters
to numbers only - and if the value is a integer, it will still work.

Tested by adding waypoints on the map & messing with the GPS coordinates.
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

Update for new Clang errors

Fix layout of mission item status values

Fix Message Indicator display