fixed problems with porous media and changed Kernel and Parameters for DLC Testcase

src/VirtualFluids_GPU/Calculation/UpdateGrid27.cpp

src/VirtualFluids_GPU/GPU/CalcMac27.cu

src/VirtualFluids_GPU/GPU/VelocityBCs27.cu

src/VirtualFluids_GPU/LBM/LB.h

src/VirtualFluids_GPU/LBM/Simulation.cpp

src/VirtualFluids_GPU/LBM/Simulation.h

src/VirtualFluids_GPU/Output/FileWriter.cpp

src/VirtualFluids_GPU/Output/UnstructuredGridWriter.hpp

targets/apps/HULC/main.cpp