Finish the offline IM module (still needs a server). Add rudimentary

support for the mute list (no functionality yet, but allows the
RetrieveInstantMessages event to fire now).

OpenSim/Framework/IClientAPI.cs

@@ -1133,6 +1133,7 @@ namespace OpenSim.Framework
         void SendUserInfoReply(bool imViaEmail, bool visible, string email);
         
         void SendUseCachedMuteList();
+        void SendMuteListUpdate(string filename);
 
         void KillEndDone();