support for composite Destinations

When subscribing to, say, your stock portfolio on a topic it would be much better to subscribe to a single destination...

STOCKS.IBMW+STOCKS.MSFT+STOCKS.BEAS

Rather than having 3 separate subscriptions. From the JMS Providers perspective this is much cheaper too!

So we could support this easily by using a special token in destinations (say +) and just patching the Filter parser.

(We'd also need to watch for this in Queue based dispatching such as how we do wildcard queue dispatching)

Also on the publishing side of things, if we publish to a composite queue it could provide fine grained control over different queues as an alternative to durable topics. e.g. so folks can explicitly browse the queues, can delete any item in the queue, can have many consumers per queue etc.