I've moved Typeable instances so that they are
either in the module that defines the type
or in the Typeable module (which defines the class)

GHC dislikes "orphan" instances, and even for humans
this makes it easier to find.

I have continued to use the INSTANCE_TYPEABLE macros,
rather than GHC's deriving( Typeable ) mechanism, so
that it'll still work for Hugs and NHC.  Nevertheless,
I may well have missed some Hugs- or NHC-specific imports,
for which I apologise.  Malcolm, Ross you may want to try
a fresh build.