Allows change/changing notifications to be delayed

Simple API:

using (reactiveObject.DelayChangeNotifications()) {
  // change a bunch of properties
} // notifications will fire
address comments
Merge branch 'rxui6-master' into add_delay_change_notifications_to_RO
Merge branch 'rxui6-master' into add_delay_change_notifications_to_RO
boolean logic is tough stuff, so many different possible options!
Add a test for delaying notifications
Test recursive acquiring the delay
Close the window as soon as we start delaying notifications
Make sure we only kick things off on first delay
Merge branch 'add_delay_change_notifications_to_RO' into rxui6-master