message: fix memory leak when specifying a single material on a geometry
diff: @@ -38,7 +38,9 @@ namespace ospray {
  }
  OSPMaterial ospMat = (OSPMaterial)mat;
  - setMaterialList(new Data(1, OSP_OBJECT, &ospMat));
  + auto *data = new Data(1, OSP_OBJECT, &ospMat);
  + setMaterialList(data);
  + data->refDec();
  }
  void Geometry::setMaterialList(Data *matListData)
  