add gravity_spheres_isosurface to selectable scenes in ospExamples
add gravity_spheres_isosurface to selectable scenes in ospExamples

ospray/OSPRay,wilsonCernWq/ospray,wilsonCernWq/ospray,wilsonCernWq/ospray,ospray/OSPRay,ospray/OSPRay,ospray/OSPRay