Add support for bearing measurement to Marble's measure tool:

• Use this UI file for the new measuretool plugin configuration dialog:

http://byte.kde.org/~tackat/MeasureConfigWidget.ui

• depending on which checkbox is checked show the distance and/or the bearing as the label (at the same position where the distance is currenly rendered) If both are checked then the bearing should be rendered in a second separate line like this:

http://byte.kde.org/~tackat/bearing.png

(colors in the mockup are not correct and should be left as they are right now)

For calculating the bearing you can use

qreal GeoDataCoordinates::bearing( const GeoDataCoordinates &other, Unit unit = Radian, BearingType type = InitialBearing ) const;