Format code. #mania
Add the `Hoa\Iterator\Counter` iterator.

This is simply a counter:

    foreach(new Hoa\Iterator\Counter(2, 15, 3) as $v)
        var_dump($v);

    /**
     * Will output:
     *     int(2)
     *     int(5)
     *     int(8)
     *     int(11)
     *     int(14)
     */