message: Remove cube generator vertex normals
  Current normals are too severe and introduce artifacts.
diff: @@ -80,19 +80,6 @@ namespace ospray {
  quads_node->add(quad_colors);
  -#if 0 //todo, debug odd rendering/lighting error on +Z plane
  - auto quad_normals = std::make_shared<DataVector3f>();
  - quad_normals->setName("normal");
  -
  - quad_normals->v.resize(quad_vertices->v.size());
  -
  - static const vec3f origin(0,0,0); //todo support arbitrary normal origin
  - for (unsigned int i=0; i < quad_normals->v.size(); i++) {
  - quad_normals->v[i] = normalize(origin - quad_vertices->v[i]);
  - }
  - quads_node->add(quad_normals);
  -#endif
  -
  // finally add to world
  #if 1 // QuadMesh or TriangleMesh?
  @@ -120,7 +107,6 @@ namespace ospray {
  tris_node->add(quad_vertices);
  tris_node->add(tri_indices);
  tris_node->add(quad_colors);
  - tris_node->add(quad_normals);
  world->add(tris_node);
  #endif
  