Galois

• Adds changed property to ControlProperty that returns ControlEvent of user generated changes.
  • textField.text.changed.map { "User changed text to \($0)" }
• Adds optional overloads for from operator. let num: Int? = 3; let sequence = Observable.from(num)
• Improves UIBindingObserver by tolerating binding from non main dispatch queue. In case binding is attempted
  from non main dispatch queue it will be automagically dispathed async to main queue.
• Makes control property naming consistent for UIDatePicker, UISearchBar, UISegmentedControl, UISwitch, UITextField, UITextView (value property + value alias name).
• Adds missing extension to UIScrollView.
  • didScroll
  • didZoom
  • didEndDecelerating
  • didEndDragging
  • didScrollToTop
• Renames refreshing to isRefreshing.
• adds UIWebView extensions:
  • didStartLoad
  • didFinishLoad
  • didFailLoad
• Adds UITabBarController extensions
  • willBeginCustomizing
  • willEndCustomizing
  • didEndCustomizing
  • didSelect
• Adds UIBarButtonItem extensions
  • title
• Performance optimizations
• Improves data source behavior by clearing data source proxy when forwarding delegate is nil.

Anomalies

• Fixes anomaly caused by UITableView invalid state caching of previous data source even after the change.
  Binding of reactive data source now triggers layoutIfNeeded that invalidates that internal cached state.
• Fixes issue with race in AnyRecursiveScheduler. #995