Marble: Replace EARTH_RADIUS by map()->model()->planet()->radius() where reasonably possible
completed by: Ilya Kowalewski
mentors: Dennis Nienhüser, shentey, Sanjiban Bairagya, Torsten Rahn
There are still lots of instances of the constant EARTH_RADIUS in the code base.
This is especially bad for code which is supposed to work for other planets.
Please find those instances and replace as many instances as possible. This should only be done in classes where knowledge about "map" or "widget" is assumed.