requestAnimationFrame

This release changes the auto-digest feature to digest on the next animation frame (using requestAnimationFrame) rather than the next tick (using setTimeout). The purpose of this change is to make it so reactive functions that do DOM manipulation only execute as frequently as necessary to update the display. Doing DOM updates more frequently than every animation does not make sense. For a more detailed discussions about this see datavis-tech/reactive-model#9 (comment)