added averaging and turbViscosity to wall model

apps/gpu/LBM/BoundaryLayer/BoundaryLayer.cpp

src/gpu/GridGenerator/grid/GridBuilder/GridBuilder.h

src/gpu/GridGenerator/grid/GridBuilder/LevelGridBuilder.cpp

src/gpu/GridGenerator/grid/GridBuilder/LevelGridBuilder.h

src/gpu/VirtualFluids_GPU/Calculation/UpdateGrid27.cpp

...tructureInitializer/GridReaderGenerator/GridGenerator.cpp

src/gpu/VirtualFluids_GPU/GPU/CudaMemoryManager.cpp

src/gpu/VirtualFluids_GPU/GPU/GPU_Interface.h

src/gpu/VirtualFluids_GPU/GPU/GPU_Kernels.cuh

src/gpu/VirtualFluids_GPU/GPU/LBMKernel.cu

src/gpu/VirtualFluids_GPU/GPU/StressBCs27.cu

.../VirtualFluids_GPU/PreCollisionInteractor/Probes/Probe.cu

...u/VirtualFluids_GPU/PreCollisionInteractor/Probes/Probe.h