Derivation for the Typeable class, as described in the Scrap Your Boilerplate papers. This derivation generates instances for all kinds of TypeableK classes; as such we do NOT require the GHC-specific generic downkinding instances to provide lower kind instances.

The generated TypeRep uses only the base name of the type, so identically named types in different modules can be treated as the same, with disasterous consequences.

Also creates a typename_<the type name> value to hold the TypeRep.