Utility to generate interpolation weights for OASIS-MCT

1) Read mask, grid and areas files, at OASIS format
   Convention for mask are those of Oasis : 0 for sea, 1 for land

2) Generates interpolation weights

3) Write them at Oasis format

4) Write some diagnostic fields in NetCDF format


@author Olivier MARTI, june 1996

Modification : Olivier MARTI, may 1997 : LMDZ case, from L. Li
               Eric GUILYARDI, may 1999 : Gaussian Grid + ORCA
               Olivier MARTI and Jacques BELLIER, april 2000 : use of polygon matching to compute weights
	       Olivier MARTI, 2000-2017