Merge branch 'feature/scalar-based-NSE' into 'master'

TurTLE/test/profiler/Kraichnan_scalar_v1.cpp

TurTLE/test/profiler/scalar_evolution.cpp

cpp/field.cpp

cpp/field.hpp

cpp/full_code/NSE.cpp

cpp/full_code/NSE.hpp

cpp/full_code/NSE_alt_dealias.cpp

cpp/full_code/get_3D_correlations.cpp

cpp/full_code/symmetrize_test.cpp

cpp/kspace.cpp

cpp/kspace.hpp

cpp/vorticity_equation.cpp

examples/ou_solver/ornstein_uhlenbeck_process.cpp

examples/ou_solver/ou_vorticity_equation.cpp