[RFC] Started initial work on sendMulti

This is just my idea of how the method should look. It should work serially for all adapters and the event system should still be called. Now the trick is to override this method in adapters that support parallel requests...

Feel free to comment or criticize. I am not hung up on this being the way to do it.
Do you think a full request object needs to be sent as the second argument? Can we get away with just sending the URL?