public void updateNorth(final float northHeading, final float cacheHeading) {
        northMeasured = northHeading;
        cacheHeadingMeasured = cacheHeading;
    }
Update north and cache headings. This method may only be called on the UI thread.

@param northHeading the north direction (rotation of the rose)
@param cacheHeading the cache direction (extra rotation of the needle)
main/src/main/java/cgeo/geocaching/ui/CompassView.java