More bug fixes resulting from trying to load small programs into Hugs
using the GHC Prelude:

-- Better handling of kinds on class method types.  It's still a kludge
   (I reckon) but works well enough to correctly handle methods in
   Monad and Functor.  See comment in startGHCClass() in interface.c.

-- Add hugsprimReadField and hugsprimShowField.

-- Make error be exported from the Prelude.  For some reason, PrelErr.hi
   doesn't give a signature for error, so we have to fake it by copying
   that of hugsprimError.

-- Handle fixity declarations read from interfaces.

-- Set nameListMonad so that list comprehensions can be translated.