An implementation of unsplat that allows for prefacing arguments

The original supported:

    unsplat(function (args) { ... })

The revision supports that, plus:

    unspat(function (first, args) { ... })
    unspat(function (first, second, args) { ... })
    unspat(function (first, second, third, args) { ... })

Very similarly to CoffeeScript's `(first, args...) -> ...` or Ruby's `def foo first, args*`