Add torture tests to test adding 10,000, 100,000 and 200,000 single prim scene objects.

These can be run using the "nant torture" target.  They are not part of "nant test" due to their long-run future nature.
Such tests are designed to do some testing of extreme situations and give some feedback on memory usage, etc.
However, data can be inconsistent due to different machine circumstances and virtual machine actions.
This area is under development.

OpenSim/Region/Framework/Scenes/SceneGraph.cs

@@ -357,7 +357,13 @@ namespace OpenSim.Region.Framework.Scenes
                 return false;
 
             if (Entities.ContainsKey(sceneObject.UUID))
+            {
+//                m_log.DebugFormat(
+//                    "[SCENEGRAPH]: Scene graph for {0} already contains object {1} in AddSceneObject()",
+//                    m_parentScene.RegionInfo.RegionName, sceneObject.UUID);
+                
                 return false;
+            }
             
 //            m_log.DebugFormat(
 //                "[SCENEGRAPH]: Adding scene object {0} {1}, with {2} parts on {3}",