Added Typeable instances, removed TypeUniverse and friends

I added `deriving Typeable` clauses to `Construct`, `AST`, `(:+:)`, `Empty`, and `BindingT`, as requested in issue #11. I removed TypeUniverse.hs, the TypeUniverse folder, and the `Dynamic.hs` benchmark for TypeUniverse.

(This is my first contribution to a project on github, so forgive me if I've done something horribly wrong)