Reimplemented artificial horizon:
uses paintEvent to draw the artificial horizon, no more need for images.
Changed scene->invalidate for viewport->update.
Changed way to pilot horizon with the mouse (ie. reimplemented mousemoveevent).
Fixed drawing moving parts: using drawChord with the correct rect and angles.
Improved drawing speed by using a pixmap for the frame of the artificial horizon.
Added triangle on top of the inner circle
Added indicator.
Renamed foregroundPixmap to backgroundPixmap, more appropriate.
Replaced setPitch/setRoll by setRollPitch.
Added scale.
Changed use of background image: now foreground image with a mask so that the center is the artificial horizon moving part.
Changed size of graduations.
Changed test from using mouse to using timer.
Fixed problem when pitch > INNERCIRCLERADIUS => arccos was NAN.
Modified way to draw moving part: now is square pixmap, easier, faster than drawing circle slices.
Added new steps in test function.
Changed scale directly drawn on the moving part of the artificial horizon.