Hide RHS of TFs with non-exported right hand sides

Not sure what to do about data families yet, since technically it would
not make a lot of sense to display constructors that cannot be used by
the user.
Add UnicodeSyntax alternatives for * and ->

I could not find a cleaner way to do this other than checking for
string equality with the given built-in types. But seeing as it's
actually equivalent to string rewriting in GHC's implementation of
UnicodeSyntax, it's probably fitting.
Display minimal complete definitions for type classes

This corresponds to the new {-# MINIMAL #-} pragma present in GHC 7.8+.
I also cleaned up some of the places in which ExportDecl is used to make
adding fields easier in the future.

Lots of test cases have been updated since they now render with
minimality information.
Strip links from recently added html tests

These were accidentally left there when the tests were originally added
Update changelog