implement client socket type and drop messages when more flag is set on client and server

src/session_base.cpp

@@ -56,6 +56,7 @@ zmq::session_base_t *zmq::session_base_t::create (class io_thread_t *io_thread_,
     case ZMQ_PAIR:
     case ZMQ_STREAM:
     case ZMQ_SERVER:
+    case ZMQ_CLIENT:
         s = new (std::nothrow) session_base_t (io_thread_, active_,
             socket_, options_, addr_);
         break;