Map and filter to array (#27)

[rstacruz]

See #27 :) This one does NOT update README.md with documentation... I had no idea how to do that. Nonetheless they should be well documented via jsdoc.

const mapToArray = require('object-loops/map-to-array')
const map = require('object-loops/map')

mapToArray({ a: 1, b: 2, c: 3 }, n => n * n)
//=> [ 1, 4, 9 ]

map({ a: 1, b: 2, c: 3 }, n => n * n)
//=> { a: 1, b: 4, c: 9 }

These functions will be helpful in dealing with React. Like this:

const ListPeople = () => {
  people = {
    john: "John Lennon",
    ringo: "Ringo Starr"
  }

  // A regular `map()` would break things here. It needs to return an array.
  return <div>
    {mapToArray(people, (name, id) => <li id={id}>Mr. ${name}</li>)}
  </div>
}

[rstacruz]

It might be worth noting that this is the same behavior of lodash/underscore's _.map.