Fixed bug in zonkExpr.
Added type annotation to HOAS and FOAS Lambda constructor to preserve monotyping.
Some missing cases for n-tuples.
Add infix declarations, zipWith and foldAllS. Fix (^).
Make Ord and Eq instances test for alpha equivalence.
Fix bug in FOASTyped.showExpr.
Add pass to for rewriting redundant tuple expressions.

Rewrites `(fst e, snd e)' to `e', and similarly for larger tuples. Expressions like this are introduced by the Computable instances for tuples.
Add Unit primitive to the language and add Computable instance for ().
Add some missing cases to HOAS.showExpr (though it is still woefully incomplete).