Added custom notification targets, geofencing notifications,
and proxy changes.
+ Area.java: Immutable geographic area object
+ MainController.java: Trying a new approach to proxies
+ NotifierController.java, NotifierUI.fxml: Added custom notifications
  and geofencing
+ Prefs, PrefsController, PrefsUI: Remove code for unused preferences
+ GeoOptionsDialog.{java,fxml}: New dialog that supports specifying a
  geographic area
+ NotifyOptionsDialog.{java,fxml}: New dialog that supports specifying
  a cusotm mail address and subject line
+ RW.java: Support Area objects
+ Trigger.java: Restructure evalPredicate and add a Result object
  that describes the output of evalPredicate
+ Documentation updates and additions