Merge branch 'feature/test_collisions' into 'develop'

CMakeLists.txt

TurTLE/DNS.py

TurTLE/_base.py

TurTLE/test/collisions/NSVE_Stokes_growing_subset.cpp

TurTLE/test/collisions/NSVE_Stokes_growing_subset.hpp

.../test/collisions/p2p_stokes_collisions_growing_subset.hpp

...test/collisions/stokes_collisions_with_background_rhs.cpp

...test/collisions/stokes_collisions_with_background_rhs.hpp

TurTLE/test/collisions/stokes_rhs.cpp

TurTLE/test/collisions/stokes_rhs.hpp

TurTLE/test/test_Heun_p2p.py

TurTLE/test/test_collisions.py

TurTLE/test/test_particle_deleter.py

cpp/field.cpp

cpp/hdf5_tools.cpp

cpp/particles/interpolation/abstract_particle_set.hpp

cpp/particles/lock_free_bool_array.hpp

cpp/particles/particles_output_sampling_hdf5.hpp

setup.py.in