- fix wrong indices in old (non Flux-Form) diffusion default S/R diffus.F   (dxG(I+1, ...) changed to dxG(I, ...), no impact on Lat-Lon grid) - use maskInW & maskInS in biharmonic diffusion (same as in gad_del2.F):   this affects results of test-exp seaice_obcs.
- fix wrong indices in old (non Flux-Form) diffusion default S/R diffus.F
  (dxG(I+1, ...) changed to dxG(I, ...), no impact on Lat-Lon grid)
- use maskInW & maskInS in biharmonic diffusion (same as in gad_del2.F):
  this affects results of test-exp seaice_obcs.

altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h,altMITgcm/MITgcm66h