New module Data.Functor.FlipT

Flip arguments of a type, this enables to create instances like
"Functor (FlipT (,) a)". Unfortunately it requires few language
extensions, namely FlexibleInstances and FlexibleContexts.
New module Data.Monoid.Endo; version bumped to 0.4

Utilities for Endo data type from Data.Monoid module.