- sbobp (global mean ocean bottom pressure ?) computation was strange ;   => change it ; also remove few unused variables. - should use array "rA" for grid-cell area (instead of dyF*dxF)
- sbobp (global mean ocean bottom pressure ?) computation was strange ;
  => change it ; also remove few unused variables.
- should use array "rA" for grid-cell area (instead of dyF*dxF)

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