Add OuterQueue interface

[rybakit]

interface OuterQueue extends Queue
{
    /**
     * @return Queue
     */
    public function getInnerQueue();
}

class TypeSafeQueue implements OuterQueue
{
    ...
}

or

interface QueueAware
{
    /**
     * @return Queue
     */
    public function getQueue();
}

class TypeSafeQueue implements Queue, QueueAware
{
    ...
}