Add object methods

adds `map()`, `reduce()`, `reduceRight()`, `forEach()` and `filter()` for objects.
```js
fast.map({a: 1, b: 2}, function (item) {
  return item + 1;
}); //=> {a: 2, b: 3}
```

also allows:

```js
var map = require('fast.js/map'); // accepts obj or array
// or 
var map = require('fast.js/array/map'); // specialized
// or
var map = require('fast.js/object/map'); // specialized
```