pipes-4.0.0

• No more proxy transformers and no more p type parameter. Instead of a type class you have a concrete Proxy type. This also means no more runIdentityP.
• The default API is a simpler unidirectional subset of the original API (which means no more () arguments).
• The module hierarchy has been moved under Pipes
• The API and module hierarchy is much smaller (~ 1/3 the original size), mostly as a consequence of the previous two changes.
• Prelude functions have simpler names but are no longer exported by default
• New polymorphic type synonyms to simplify type signatures.