ver 5.4.1

This release is available in AssetStore on 2016-09-08
https://www.assetstore.unity3d.com/jp/#!/content/17276

Improvement: Support Unity 5.5 Beta
Fix: ThrottleFirstFrame throws NullReferenceException when stream sends OnNext immediately. #160, thanks @hsanno
Fix: Error on LogEntry.cs #164, thanks @kimsama
Fix: ToReadOnlyReactiveProperty should be distinct publishing #161
Fix: To(ReadOnly)ReactiveProperty cause strange result when source observable returns OnCompleted or OnError
(Breaking) Changes: PresenterBase was obsoleted(but it only commented, not marked [Obsolete])
Breaking Changes: Sample14 was removed
Breaking Changes: Removed ObservableMonoBehaviour, TypedMonoBehaviour in UNITY 5.5 or newer