Default netCDF fileformat? #139
Description
At present, our output netCDFs default to netCDF4-classic. Should this be netCDF4?
Worth considering that ANTS netCDFs are (typically) only loaded via ANTS or via UKCA - the rest of the UM only loads F03 ancillary files derived from the netCDF files. UKCA has a bespoke saver, so does not need to use the same format as the default netCDF saver.
Suspect this could be an easy change to make, but it may be a tricky one to validate with all users.
Also worth considering (either in this issue, or a spin off issue) whether we should be enabling netCDF compression.