In SSYDocFileObserver, added a new kqueue flag, SSYPathObserverChangeFlagsDelete (NOTE_DELETE) to the existing kqueue flag SSYPathObserverChangeFlagsRename (NOTE_RENAME) as the change criteria which are watched for.  This makes the change detection more sensitive.  In particular, it now detects file updates by ChronoSync in addition to file updates by Dropbox.  Plus other changes in the course of BookMacster 1.20.2.