Patch from Michael Osias IBM (jimbo2120)

In his own words: 
If a prim becomes a listener or remote channel and the script is deleted, it cannot become a listener or channel again with a new script.  
This patch fixes that.

OpenSim/Region/Environment/Interfaces/IXMLRPC.cs

@@ -39,5 +39,6 @@ namespace OpenSim.Region.Environment.Interfaces
         RPCRequestInfo GetNextRequest();
         void RemoteDataReply(string channel, string message_id, string sdata, int idata);
         bool IsEnabled();
+        void DeleteChannel(LLUUID itemID);
     }
 }