bug fix: replace SEAICE_rhoSnow by SEAICE_rhoIce in the Rothrock          (1975)-type strength calculations
bug fix: replace SEAICE_rhoSnow by SEAICE_rhoIce in the Rothrock
         (1975)-type strength calculations

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