nbody: remove unused top row buttons from gui, and print iterations in gui instead of to console
nbody: remove unused top row buttons from gui, and print iterations in gui instead of to console

paperscape/paperscape-mapgen,paperscape/paperscape-backend,paperscape/paperscape-mapgen,paperscape/paperscape-backend,paperscape/paperscape-backend,paperscape/paperscape-mapgen,paperscape/paperscape-backend,paperscape/paperscape-mapgen