Add regression test for teleporting between neighbouring regions on the same simulator

This adds a non-advertised wait_for_callback option in [EntityTransfer].  Default is always true.
Teleport tests disable the wait for callback from the destination region in order to run within a single thread.

OpenSim/Region/ClientStack/Linden/UDP/Tests/LLImageManagerTests.cs

@@ -79,7 +79,8 @@ namespace OpenSim.Region.ClientStack.LindenUDP.Tests
 
             J2KDecoderModule j2kdm = new J2KDecoderModule();
 
-            scene = new SceneHelpers().SetupScene();
+            SceneHelpers sceneHelpers = new SceneHelpers();
+            scene = sceneHelpers.SetupScene();
             SceneHelpers.SetupSceneModules(scene, j2kdm);
 
             tc = new TestClient(SceneHelpers.GenerateAgentData(userId), scene);

OpenSim/Region/ClientStack/RegionApplicationBase.cs

@@ -111,7 +111,7 @@ namespace OpenSim.Region.ClientStack
                     server.Start();
                 }
             }
-
+            
             base.StartupSpecific();
         }