- allow to use EXF_ZENITHANGLE without pkg/cal - simplify (saving some calculations) and improve indentation
- allow to use EXF_ZENITHANGLE without pkg/cal
- simplify (saving some calculations) and improve indentation

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