* Made controller.Notebooks.save_note() return the newly minted revision timestamp upon a successful save.
* Whenever we get back a revision timestamp from save_note(), we store in in the client's list of revisions for that note.
* Now raising Access_error in controller.Notebooks in various places where the notebook requested is unknown.
* Tweaked pulldown CSS a bit. Now will sport a handy-dandy scrollbar if the pulldown gets too tall, at least in real browsers.
* Fixed bug where clicking "show on startup" checkbox directly didn't visually toggle the checkbox.
