Allow named queues with .animate()

[[email protected]…]

Just to float an idea I've been having, sometimes you want to have separate queues for separate elements. jQuery supports multiple named queues, of course, and the queue that .animate() places animations on if it's told to is the queue named 'fx'. How about allowing the queue parameter to be a string, and if it is, it specifies the name of the queue on which to place the animation? That way it's convenient to queue up animations for different elements.

[boushley]

Duplicate of #7490.