Merge branch 'master' into fluidizedbed_showcase

.gitignore

apps/tutorials/basics/01_BlocksAndFields.cpp

apps/tutorials/pe/02_ConfinedGasExtended.cfg

apps/tutorials/pe/02_ConfinedGasExtended.cpp

apps/tutorials/pe/02_ConfinedGasExtended.dox

src/core/mpi/MPIWrapper.h

src/pe/ccd/HashGrids.cpp

src/pe/ccd/HashGrids.h

src/pe/raytracing/Color.cpp

src/pe/raytracing/Color.h

src/pe/raytracing/Intersects.h

src/pe/raytracing/Lighting.h

src/pe/raytracing/Ray.cpp

src/pe/raytracing/Ray.h

src/pe/raytracing/Raytracer.cpp

src/pe/raytracing/Raytracer.h

src/pe/raytracing/ShadingFunctions.h

src/pe/raytracing/ShadingParameters.h

...hange_method/restoration/ExtrapolationDirectionFinder.cpp

...xchange_method/restoration/ExtrapolationDirectionFinder.h