As done on the trunk in previous commit [5152]:
Removed interpolation from grid_nsnow and created new grid_nsnow2 which keeps the interpolation as before. Then use grid_nsnow2 when interpolation is needed for the input files but not for the output variables.
This is done because the filter id="greordered" do not work together with the interpolation, added in the trunk rev [5101].
This will be done on the trunk and the tag ORCHIDEE_2_0 because needed for CMIP6 workflow.