* Made sure the trash is not exposed by the read-only notebook view.
* Modified model.User.check_access() to consider read-write access to a
notebook to be sufficient for access to that notebook's trash.
* Modified controller.Users so new users are created with a notebook that
has a trash.
* Changed controller.Notebooks so deleted notes go to the trash (if any).
* is_startup_note() checks whether the object id of the given note is in the list of startup notes,
not whether the actual object is.
* This fixed a bug in which the same note could be saved to the list of startup notes multiple
times, thereby causing funny display problems when the same note was loaded twice.
