netCDF format for DB import

when reading the netcdf files with python engine h5netcdf, an error occur. It seems that the netcdf files produced are in netcdf3 format. We need at least netcdf4 to be able to use h5netcdf engine that enables reading files on the S3 in lazy mode.

nccopy -k netCDF4 safran_maize_pluv.nc safran_maize_pluv_nc4.nc solves this.

But an integrated patch in the optirrig package would be better. We should investigate this.