Window Sink to initiate Pipeline Stop and main-loop quit if there are no added "Delete Event Handlers"

[rjhowell44]

Currently, the client must register a Delete Event Handler to be called on window delete event (close) and stop the Pipeline and quit the main-loop.

Changing the default behavior of the Window Sinks to send an application message to the Pipeline State Manager to handle the pipeline stop and quit the main-loop if there are no registered client handlers.