Problem: typo in comment in proxy.cpp

Solution: fix it

src/proxy.cpp

@@ -171,7 +171,7 @@ static int loop_and_send_multipart_stat (zmq::socket_base_t *control_,
     msg.init_size (sizeof (uint64_t));
     memcpy (msg.data (), (const void *)&stat, sizeof (uint64_t));
 
-    //  if the first message is handled to the pipe successfully then the HWM
+    //  if the first message is handed to the pipe successfully then the HWM
     //  is not full, which means failures are due to interrupts (on Windows pipes
     //  are TCP sockets), so keep retrying
     do {