Extend VTK Writer

apps/benchmarks/NonUniformGridCPU/NonUniformGridCPU.cpp

...s/NonUniformGridCPU/simulation_setup/benchmark_configs.py

apps/benchmarks/NonUniformGridGPU/NonUniformGridGPU.cpp

apps/benchmarks/UniformGridCPU/UniformGridCPU.cpp

apps/benchmarks/UniformGridGPU/UniformGridGPU.cpp

src/vtk/VTKOutput.cpp

src/vtk/VTKOutput.h