0.25.0-beta2

• Internal refactoring Stream Transformers.
• Fixed RetryStream example documentation.
• Error thrown from DeferStream factory will now be caught and converted to Stream.error.
• doOnError now have strong type signature: Stream<T> doOnError(void Function(Object, StackTrace) onError).
• Updated ForkJoinStream:
  • When any Stream emits an error, listening still continues unless cancelOnError: true on the downstream.
  • Pause and resume Streams properly.
• Added UsingStream.
• Updated TimerStream: Pause and resume Timer when pausing and resuming StreamSubscription.