Fades the animation with name animation in over a period of time seconds and fades other animations out.
If mode is PlayMode.StopSameLayer, animations in the same layer as animation will be faded out while animation is faded in.
if mode is PlayMode.StopAll, all animations will be faded out while animation is faded in.
If the animation is not set to be looping it will be stopped and rewound after playing.