message: Refactor ZMQROOTmerger
  add handling of AliMergeable
  don't use TMap
diff: @@ -675,6 +675,14 @@ Int_t DoReceive(aliZMQmsg::iterator block, void* socket)
  delete container;
  break;
  }
  + AliMergeable* unpackable = dynamic_cast<AliMergeable*>(object);
  + if (unpackable) {
  + if (fVerbose) printf("unpacking custom AliMergeable container %p\n", unpackable);
  + GetObjects(unpackable, &fListOfObjects);
  + if (fVerbose) printf("deleting custom AliMergeable container %p\n", unpackable);
  + delete unpackable;
  + break;
  + }
  }
  if (TCollection* collection = dynamic_cast<TCollection*>(object)) {
  @@ -838,6 +846,7 @@ Int_t DoSend(void* socket)
  aliZMQmsg messageCopy;
  alizmq_msg_copy(&messageCopy, &message);
  sentBytes += alizmq_msg_send(&messageCopy, fZMQresetBroadcast, 0);
  + fNumberOfMessagesSent++;
  if (fVerbose) printf("a copy was broadcasted, %i bytes\n", sentBytes);
  alizmq_msg_close(&messageCopy);
  }
  