Weakly connected status announcement. (#135)

* Forward others' messages only to the weakly connected nodes instead of broadcasting to all the connected peers.
* Announcing connected status depends on a threshold to other connected peers.
* Forwarding messages of weakly connected peers to other peers.

src/comm/comm_session.cpp

@@ -179,6 +179,7 @@ namespace comm
             if (out_msg_queue.try_dequeue(msg_to_send))
             {
                 process_outbound_message(msg_to_send);
+                util::sleep(1);
             }
             else
             {