use explicit refinementIntervals in subsampling vtk writer

amdis/io/VTKWriter.hpp

@@ -78,7 +78,7 @@ namespace AMDiS
       auto subSampling = Parameters::get<int>(name + "->subsampling");
       if (subSampling) {
         using SubsamplingWriter = Dune::SubsamplingVTKWriter<GridView>;
-        vtkWriter_ = std::make_shared<SubsamplingWriter>(gridView, subSampling.value());
+        vtkWriter_ = std::make_shared<SubsamplingWriter>(gridView, Dune::refinementIntervals(subSampling.value()));
       } else {
         vtkWriter_ = std::make_shared<Writer>(gridView);
       }