The Tweenable interface allows modifying an object's attributes smoothly over time using
Tween instances managed by the
An interface to generally apply a function to a value.
A Tween is an interpolation between start values and target values over a given time period.
The TweenEngine is the central manager for Tweens.
Easing equations based on Robert Penner's work: http://robertpenner.com/easing/
The TweenType determines which values of a Tweenable} will be modified by a