Merge branch 'bugfix/clean-up-old-code' into develop

bfps/DNS.py

bfps/FluidConvert.py

bfps/NSManyParticles.py

bfps/NSVorticityEquation.py

bfps/NavierStokes.py

bfps/PP.py

bfps/TEST.py

bfps/__init__.py

bfps/__main__.py

bfps/_fluid_base.py

bfps/cpp/distributed_particles.cpp

bfps/cpp/distributed_particles.hpp

bfps/cpp/fftw_tools.cpp

bfps/cpp/fftw_tools.hpp

bfps/cpp/fluid_solver.cpp

bfps/cpp/fluid_solver.hpp

bfps/cpp/fluid_solver_base.cpp

bfps/cpp/fluid_solver_base.hpp

bfps/cpp/full_code/NSVE.cpp

bfps/cpp/full_code/NSVE.hpp