Methods for subsequent memory leak fixes

Background
-----
This pull request represents a smaller chunk of a larger work (happening on [Plumber branch](https://github.com/Benglin/Dynamo/tree/Plumber)), making code review process more manageable. It exposes methods that will be called eventually when the full memory leak fix goes in, but for now, these new methods are not called in anyway.
This method is called by ```InstrumentationLogger.End``` method (which is in turn called by ```dynSettings.DestroySessionSingletonObjects``` method that will be introduced with later submissions).