Marble: fix planet order
completed by: Illya Kovalevskyy
mentors: Torsten Rahn, René Küttner, Dennis Nienhüser
Currently the order of the Planets that show up in the "Celestial Body" Combobox is wrong. Please fix this
The regular order should be:
Pluto (yes we still love you!)
All other bodies (Io etc.) should appear alphabetically only after this list. Ideally there would be a non-clickable separation line between the planet category and the rest.