add animation helper, which simplify the use of animate.css, also support handle a list of elements

4 helper functions add:

animateOnce(): Animate an element once with give animation name.
animateOnceWithFadeInDelay(): Fade in an element once with give animation name and given time delay.
fadeInElementList(): Fade in a list of elements in list order with  give animation.
fadeInElementListRandom(): Fade in a list of elements randomly with  give animation.

See helper/test.html for demo
For helper API and usage please look into the in js JSdoc comments.