* Storyviews expose a static "singleTiddlerMode" property to determine if they require single tiddler mode
* Navigator widget adds a "singleTiddlerMode" attribute; when set to "yes", the story list is entirely replaced during navigation
* Navigator widget now updates "list" field of $:/HistoryList with a more accessible version of the history list
* Add a getstoryviewsingletiddlermode[] operator so that we can obtain the story view STM status for passing to the navigator widget
