History 2.6.0 / 2018-11-26 add CSSMotion component 2.3.0 / 2016-07-05 support null/undefined child: react-component#11 2.2.0 / 2016-06-28 support transitionName as object 2.1.0 / 2016-06-16 make onEnter/onLeave/onAppear async