Coupling field names for OASIS should not be limited to 8 characters

[ufla]

The length of OASIS coupling field names is limited to 8 characters in OPA_SRC/SBC/cpl_oasis3.F90:

TYPE, PUBLIC ::   FLD_CPL               !: Type for coupling field information
   [...]
   CHARACTER(len = 8)    ::   clname    ! Name of the coupling field   
   [...]
END TYPE FLD_CPL

However, the limit for coupling field names has been increased to 128 characters in OASIS3 a while ago, hence there should be no reason for NEMO to have a lower limit.

This is particularly important in the context of multi-category coupling fields (i.e. for LIM3), which need extra space in the character string for sequential numbering.

[timgraham]

This is very similar to ticket #1343. I will try to apply the fix for that later today but in the meantime I will close this ticket as a duplicate.

[smasson]

This will be done in the next release when moving the coupling interface from oasis3 to oasis3-mct. Note that because of this change, next release will no more be compatible with oasis3.