ver 5.3.0

This release is available in AssetStore on May13th 2016.
https://www.assetstore.unity3d.com/jp/#!/content/17276

This release introduce MicroCoroutine, it is memory efficient and 10x faster than standard coroutine at run many coroutines.
Some coroutine based operators has been changed to use MicroCoroutine.

Add : ReactiveCommand
Add : MainThreadDispatcher.StartUpdateMicroCoroutine, StartFixedUpdateMicroCoroutine, StartEndOfFrameMicroCoroutine
Add : Scheduler.MainThreadFixedUpdate, MainThreadEndOfFrame
Add : ToYieldInstruction(cancellationToken)
Add : Observer.Create(onNext/onNext, onError/onNext, onCompleted) overload
Add : IReadOnlyReactiveProperty.SkipLatestValueOnSubscribe
Add : Observable.WhenAll overload (IObservable(params IObservable[] sources), this becomes breaking changes)
Add : Observable.FromMicroCoroutine
Add : Observable.AsSingleUnitObservable
Add : Observable.SubscribeWithState
Add : Observable.CreateWithState
Add : Disposable.CreateWithState
Improvement : Use MicroCoroutine on ObserveEveryValueChanged, EveryUpdate, EveryFixedUpdate, EveryEndOfFrame, NextFrame, TimerFrame, IntervalFrame, DelayFrame, SampleFrame, ThrottleFrame, ThrottleFirstFrame, TimeoutFrame
Improvement : Performance improvement for Observable.Range, Repeat when scheduler is Scheduler.Immediate
Improvement : Use Time.unscaledDeltaTime in IgnoreTimeScaleMainThreadScheduler
Fix : ReadOnlyReactiveProperty(source, initialValue) does not publish initial value on subscribe
Fix : IReadOnlyCollection has set indexer
Fix : Ambigious property of IReactiveCollection.Count, Indexer
Fix : Throw invalid error when ObservableWWW.LoadFromCacheOrDownload failed.
Breaking Changes : Added IReadOnlyReactiveProperty.HasValue
Breaking Changes : AsyncConvertsion scheduler to Scheduler.MainThread on WebGL build(WebGL doesn't support ThreadPool)
Other : Update UniRxAnalyzer 1.4.0.1 https://www.nuget.org/packages/UniRxAnalyzer