2014-08-01-13.00.03: src/lib/x-kit/widget/leaf/arrowbutton.api: For conciseness, clarity and broad applicability, renamed  APP_TO_ARROWBUTTON_NOTIFY -> PORT_WATCHER  and  STATE_CHANGE_NOTIFY -> STATE_WATCHER.  Also added SITE_WATCHER.  (<<Watcher>> is the standard Design Patterns name for this relationship.)