public void AddListener (TradeListener listener)
{
OnError += listener.OnError;
OnTimeout += listener.OnTimeout;
OnAfterInit += listener.OnAfterInit;
OnUserAddItem += listener.OnUserAddItem;
OnUserRemoveItem += listener.OnUserRemoveItem;
OnMessage += listener.OnMessage;
OnUserSetReady += listener.OnUserSetReadyState;
OnUserAccept += listener.OnUserAccept;
OnNewVersion += listener.OnNewVersion;
OnComplete += listener.OnComplete;
listener.trade = this;
}