Allow sorting arrays which implement \ArrayAccess

[mallorydxw]

This is wrong:

    public static function sortBy($array, $callback)
    {
        if (!is_callable($callback) || !is_array($array)) {
            trigger_error('Arguments are in the wrong order', E_USER_ERROR);
        } //@codeCoverageIgnore

It should also accept classes which implement \ArrayAccess.