mesa_pd shapes are now pack- and unpackable

python/mesa_pd.py

python/mesa_pd/mpi/ShapePackUnpack.py

python/mesa_pd/mpi/__init__.py

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

...plates/mpi/notifications/ParticleCopyNotification.templ.h

src/mesa_pd/data/shape/BaseShape.h

src/mesa_pd/data/shape/Box.h

src/mesa_pd/data/shape/CylindricalBoundary.h

src/mesa_pd/data/shape/Ellipsoid.h

src/mesa_pd/data/shape/HalfSpace.h

src/mesa_pd/data/shape/Sphere.h

src/mesa_pd/mpi/ShapePackUnpack.h

src/mesa_pd/mpi/notifications/ParticleCopyNotification.h

tests/mesa_pd/CMakeLists.txt

tests/mesa_pd/mpi/ShapePackUnpack.cpp