fix copyright headers

cpp/base.hpp

cpp/env_utils.hpp

cpp/fftw_interface.hpp

cpp/fftw_tools.cpp

cpp/fftw_tools.hpp

cpp/field.cpp

cpp/field.hpp

cpp/field_binary_IO.cpp

cpp/field_binary_IO.hpp

cpp/field_layout.cpp

cpp/field_layout.hpp

cpp/full_code/Gauss_field_test.cpp

cpp/full_code/Gauss_field_test.hpp

cpp/full_code/NSVE.cpp

cpp/full_code/NSVE.hpp

cpp/full_code/NSVE_Stokes_particles.cpp

cpp/full_code/NSVE_Stokes_particles.hpp

cpp/full_code/NSVE_field_stats.cpp

cpp/full_code/NSVE_field_stats.hpp

cpp/full_code/NSVE_no_output.hpp