Change the inheritance of FixedTemperature to Surface and not SlabSurface (there was no apparent reason for having in inheriting from SlabSurface as the new attribute of SlabSurface are not used in FixedTemperature)
Update/change docstrings in Surface and Core.
Make the from_netcdf method read all parameters for the class, and add a overloading method in SlabOcean for the new parameters.