Add start GC memory and end GC memory to object stress test printouts.

This illustrates that references to Scene, SOG, etc. are not currently being released when a stress test ends (or at regression test end in general).
This means even the current stress tests take much more memory than they need, a problem that will have to be addressed.

OpenSim/Tests/Torture/ScriptTortureTests.cs

@@ -107,6 +107,8 @@ namespace OpenSim.Tests.Torture
             m_expectedChatMessages = scriptsToCreate;
             int startingObjectIdTail = 0x100;
 
+            GC.Collect();
+
             for (int idTail = startingObjectIdTail;idTail < startingObjectIdTail + scriptsToCreate; idTail++)
             {
                 AddObjectAndScript(idTail, userId);