Change values of default CCoordinateGeodetic constructor

Up to know, the default constructor initialized x=0, y=0 and z=0. This
caused problems with default initialized CCoordinateGeodetic objects
when using it in calculateGreatCircleDistance. The result was always 0.
Instead use Lat=0, Lon=0, height=0.

src/blackmisc/geo/coordinategeodetic.h

@@ -147,7 +147,8 @@ namespace BlackMisc
 
         public:
             //! Default constructor
-            CCoordinateGeodetic() = default;
+            CCoordinateGeodetic() :
+                CCoordinateGeodetic(0, 0, 0) {}
 
             //! Constructor by normal vector
             CCoordinateGeodetic(const QVector3D &normal) : m_x(normal.x()), m_y(normal.y()), m_z(normal.z()) {}