Removed IObservable#flatMap(Fn<A, IObservable<B>>) as it is pretty useless.
Added some comments to IObservable methods.
TriggerEnter2DForwarder
IRxVal#map override that returns IRxVal.
IRxRef#comap
IObservable#toFuture
Change F.unit() to F.unit.
IEnumerable#eachWithIndex.
ASync.inAsyncSeq, Future.sequence, Future.fromCoroutine