Make LLUDP output queue refill thread active by default, since load tests have shown that this has better scalability.

For testing, previous behaviour can be restored with the console command "debug lludp oqre stop" at runtime.

OpenSim/Region/ClientStack/Linden/UDP/LLUDPServer.cs

@@ -447,6 +447,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         {
             StartInbound();
             StartOutbound();
+            OqrEngine.Start();
 
             m_elapsedMSSinceLastStatReport = Environment.TickCount;
         }
@@ -491,6 +492,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             m_log.Info("[LLUDPSERVER]: Shutting down the LLUDP server for " + Scene.Name);
             base.StopOutbound();
             base.StopInbound();
+            OqrEngine.Stop();
         }
 
         protected override bool EnablePools()

OpenSim/Region/ClientStack/Linden/UDP/OutgoingQueueRefillEngine.cs

@@ -92,7 +92,7 @@ namespace OpenSim.Region.ClientStack.LindenUDP
                 "debug lludp oqre",
                 "debug lludp oqre <start|stop|status>",
                 "Start, stop or get status of OutgoingQueueRefillEngine.",
-                "Experimental.",
+                "If stopped then refill requests are processed directly via the threadpool.",
                 HandleOqreCommand);
         }