Merge branch 'feature/timeseries' into 'master'

dune/vtk/utility/uid.hh

dune/vtk/vtktimeserieswriter.hh

dune/vtk/vtktimeserieswriter.impl.hh

dune/vtk/vtkwriterinterface.hh

dune/vtk/vtkwriterinterface.impl.hh

dune/vtk/writers/vtkimagedatawriter.hh

dune/vtk/writers/vtkimagedatawriter.impl.hh

dune/vtk/writers/vtkrectilineargridwriter.hh

dune/vtk/writers/vtkrectilineargridwriter.impl.hh

dune/vtk/writers/vtkstructuredgridwriter.hh

dune/vtk/writers/vtkstructuredgridwriter.impl.hh

dune/vtk/writers/vtkunstructuredgridwriter.hh

dune/vtk/writers/vtkunstructuredgridwriter.impl.hh

src/CMakeLists.txt

src/benchmark.cc

src/datacollector.cc

src/geometrygrid.cc

src/legacyvtkwriter.cc

src/polygongrid.cc

src/structuredgridwriter.cc