Breaking Change. Event arguments [EventArgs] are now supported.

• The builder argument has been renamed to handler, to better reflect that you are supplying a subscriber handler that is called when the event is broadcast.
• A handler requires now two arguments, the first representing the BuildContext, and the second the (optional) [EventArgs] associated with the Event.
  • before: builder: (context) => Text(myCount.value.toString()),
  • after: handler: (context, args) => Text(myCount.value.toString()),

...
EventSubscriber(
  event: myCount.onValueChanged,
  handler: (context, args) => Text(myCount.value.toString()),

  // If an Event has arguments, they are now available in your handler.
  // In the example above through `args` argument.
),

IMPORTANT: args should be checked for null before use in a handler, as the handler is called BOTH when an Event occurs, and also by the Flutter framework. In the latter case, args will always be null.

• Dependency on EventNotifier removed.
• Dependency on Event added.