error when filing halos larger than the inner domain

Context

There is an error when we fill the MPI-subdomains halos with jp_fillcopy or jp_fillperio and when their size (e.g. nn_hls) is larger than the inner domain (Ni_0 or Nj_0).

Analysis

we have to make sure we don't use values that are outside of the inner domain to fill the halos.

Fix

use modulo and fill the halo from the point located next to the inner domain and going toward the outside of the domain. -> western/southern sides must be filled with do loops having an increment of -1 instead of +1.

See for example how to fill a periodic domain with Ni_0 = 2 and nn_hls = 3