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be used by sprites and animations. Ray is now thinking, "Why do we have this wacky difference between sprites and animations?" but changing it now would be a massive amount of typing that I'm not super interested in doing. In any case factoring out the "effects" into separate classes is still useful because frequently one wants to combine them in crazy ways that would not be possible with a FadeSprite or FadeAnimation. git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@3426 542714f4-19e9-0310-aa3c-eee0fc999fb1