While testing the previous commit on Windows I found that I could not
compile windows due to include of atlbase.h. This file is no longer
available in SDKs. It is only available in for money versions of VIsual
Studio. Luckily this include was not needed. So I just removed it and
Windows now builds again with just VS Express. Tested all changes on
OSX, Linux and Windows (including speech on windows, which still works).

QTBUG 34300 causes relative path references to qml file loading to fail.

Removed for compatability

flightgear hil: correct scaling of pressure for mavlink message and remove indicated airspeed from flightgear protocol, commit requires flightgear protocol update

This allows you to add XY graph plots of any data.  For example,
x,y position data of a servo.

There's no need to create multiple signals - connect() is fine with
connecting styleChanged(MainWindow::QGC_MAINWINDOW_STYLE)  to a slot
with no parameters.

Clean up when exactly we should save settings, and add in checks to make sure we do not do it incorrectly