Make Maven transfer listener used with Resolver more concurrent friendly

Current console transfer listener used in Maven has all method synchronized. This becomes a problem as resolver is more and more parallelized, and threads from it sending events are getting in race condition for maven listener monitor.

One possibility would be to implement a "demuxer" listener, that wraps another listener: it receives even from multiple threads events, returns fast, but passes the incoming events on single thread to wrapped listener. This makes resolver relieve a bit, but also keeps actual listener simple, as it can be coded single threaded.