Add regression test for teleporting an agent between separated regions on the same simulator.

This involves a large amount of change in test scene setup code to allow test scenes to share shared modules
SetupScene is now an instance method that requires an instantiation of SceneHelpers, though other SceneHelpers methods are still static
May split these out into separate classes in the future.

OpenSim/Capabilities/Handlers/GetTexture/Tests/GetTextureHandlerTests.cs

@@ -50,7 +50,7 @@ namespace OpenSim.Capabilities.Handlers.GetTexture.Tests
             TestHelpers.InMethod();
 
             // Overkill - we only really need the asset service, not a whole scene.
-            Scene scene = SceneHelpers.SetupScene();
+            Scene scene = new SceneHelpers().SetupScene();
 
             GetTextureHandler handler = new GetTextureHandler(null, scene.AssetService);
             TestOSHttpRequest req = new TestOSHttpRequest();