message: remove unused code in XYZ sg importer
diff: namespace ospray {
  namespace sg {
  - OSPData makeMaterials(OSPRenderer renderer, const particle::Model &model)
  - {
  - int numMaterials = model.atomType.size();
  - std::vector<OSPMaterial> matArray(numMaterials);
  -
  - for (int i = 0; i < numMaterials; i++) {
  - OSPMaterial mat = ospNewMaterial(renderer, "OBJMaterial");
  - ospSet3fv(mat, "kd", &model.atomType[i]->color.x);
  - ospCommit(mat);
  - matArray[i] = mat;
  - }
  -
  - OSPData data = ospNewData(numMaterials,OSP_OBJECT,matArray.data());
  - return data;
  - }
  -
  void importXYZ(const std::shared_ptr<Node> &world, const FileName &fileName)
  {
  particle::Model m;
  