More thorough extension of built-in types

[ghost]

• Ranges
• Sorted hashes and sets
• All list types
• IFn

[tcsavage]

I'm happy to implement extensions for IFn since I need it for another project, but there are two possible monoid instances:

• mappend = comp and mempty = identity
• mappend = (fn [f g] (fn [x] (mappend (f x) (g x)))) and mempty = (constantly (mempty))

As you may already be aware, the latter is Haskell's implementation (the other being defined for the Endo newtype), and it's also the one I've had the most use for personally. But which is preferable for this library specifically?

[yurrriq]

Related: #116