WinGui: Various fixes and improvements to validation handling and options in the UI.

WinGui:  Various fixes and improvements to validation handling and options in the UI.
- Fixed add to queue error handling on 2 code paths that ignored errors returned.
- AutoName will now guarantee a unique filename rather than stop after the first attempt.
- Options Pane now lists the available format and path variables that can be used in the UI (rather than the tooltip)
- Ordering of validation rules changed to be more sensible, especially when handling paths that end up same as source.