CMIP6 @IPSL: use the C ESM EP to check my MIP runs

(in progress)

The C-ESM-EP will be used at IPSL to check if the simulations produced with the DR CMIP6 for the different MIPs output correct files (at least for the list of high priority variables specified by each component).

Important note for the users: if you want to use the time manager functionality (ex: 'last_XXY' for the clim_period, 'full' for the ts_period) of the C-ESM-EP for your CMIP6 outputs (CMIP6_OUT CliMAF project), you have to use the set_available_period_ts_clim.py script. (--> the dates specified on the CMIP6 file names correspond to the start and end of the simulation specified by the user, not the years that are actually available in the file; I thus had to do a fix in set_available_period_ts_clim.py to check the real period covered by the simulation in the IGCM_OUT outputs of the simulation (TS_MO))