Instead of sourcing only one .atlas_env... divide up in three areas

[sdipsl]

This will ease our work to test new versions.

Also there is a hierarchy between those. Depending on the compiler you can or not load some netcdf or nco module (very true on ada for 2013.0 for instance).

# Take care of compiler, bullx.
.env_intel2017.2_curie
# Take care of netcdf, nco, cdo, python
.env_netcdf4.3.3.1_curie
#.env_netcdf4.4_curie
#Take of atlas related stuff
.env_atlas_curie

[sdipsl]

Done for Curie see r1409