Philippe 20/03/2024: add boxes for output files (not yet fully implemented)

src/LIB/SURCOUCHE/src/modd_field.f90

src/LIB/SURCOUCHE/src/modd_io.f90

src/LIB/SURCOUCHE/src/mode_io_field_write.f90

src/LIB/SURCOUCHE/src/mode_io_manage_struct.f90

src/LIB/SURCOUCHE/src/mode_io_tools_nc4.f90

src/LIB/SURCOUCHE/src/mode_io_write_nc4.f90

src/MNH/modd_bakout.f90

src/MNH/modd_outn.f90

src/MNH/modn_output.f90