* Changed the misc. methods calling ThreadPool.UnsafeQueueUserWorkItem() to Util.FireAndForget()

* Changed Util.FireAndForget() to use any of five different methods set with async_call_method in the [Startup] section of OpenSim.ini. Look at the example config for possible values

OpenSim/Framework/Communications/RestClient.cs

@@ -403,7 +403,7 @@ namespace OpenSim.Framework.Communications
             /// In case, we are invoked asynchroneously this object will keep track of the state
             /// </summary>
             AsyncResult<Stream> ar = new AsyncResult<Stream>(callback, state);
-            ThreadPool.UnsafeQueueUserWorkItem(RequestHelper, ar);
+            Util.FireAndForget(RequestHelper, ar);
             return ar;
         }