Change the way we deal with GHC's type-class dictionaries

The normalisation system used to have knowledge on  dictionaries,
dictionary functions, and class methods. As these aspect are
somewhat GHC-specific, this knowledge has been removed.

Consequently the GHC2Core process now create normal binders for
dictionary functions. Class methods are now translated to
global binders where the term is a simple case-statement that
selects the correct function out of the dictionary.
Show of TyCon's gives more information about their structure
Add commented expressions on translating GHC's Casts

The commented expressions add primitives that perform the cast.
At the moment hower, all transformations in the normalization
process do not take the presence of these casts into account.

Until there is a better answer for dealing with casts the
expression are left commented out.