I've added support for forwarding <iq/> requests when multiple resources are connected.

Requests will be router to the resource with highest priority (registered on the local node) and response will be routed to the original sender of the request.

This new logic can be easily disabled (rolled back to old behaviour) by setting muc-multi-item-forward-best to false.

This logic should help with vCard retrieval in semianonymous rooms when users are connected with more than one resource. Previously, that would result with an error while now it works as it should. Additionally, it is possible to use disco#info and other <iq/> based communication with routing to the resource with highest priority.

That requires changes in the ACS-MUC.

From the quick look it looks ok.