Showcase for dense particle packing

apps/showcases/CMakeLists.txt

apps/showcases/ParticlePacking/CMakeLists.txt

apps/showcases/ParticlePacking/DiameterDistribution.h

apps/showcases/ParticlePacking/Evaluation.h

apps/showcases/ParticlePacking/ParticlePacking.cfg

apps/showcases/ParticlePacking/ParticlePacking.cpp

apps/showcases/ParticlePacking/ShapeGeneration.h

apps/showcases/ParticlePacking/Utility.h

...wcases/ParticlePacking/example_meshes/sediment_scan_0.obj

...wcases/ParticlePacking/example_meshes/sediment_scan_1.obj

apps/showcases/PegIntoSphereBed/PegIntoSphereBed.cpp

python/mesa_pd.py

python/mesa_pd/templates/mpi/ShapePackUnpack.templ.h

src/mesa_pd/data/ParticleAccessor.h

src/mesa_pd/data/ParticleStorage.h

src/mesa_pd/data/shape/BaseShape.h

src/mesa_pd/kernel/InitParticlesForHCSITS.h

src/mesa_pd/kernel/IntegrateParticlesHCSITS.h

src/mesa_pd/mpi/ShapePackUnpack.h

src/mesa_pd/mpi/notifications/NumContactNotification.h