Plays an animation without any blending.
If no name is supplied then the default animation will be played. In cases where the animation can't be played
(ie, there is no default animation or no animation with the specified name), the function will return false.
The optional playMode lets you choose how this animation will affect others already playing.
If the specified animation is already playing then other animations will be stopped but the animation
will not rewind to the beginning.
When the end of the animation is reached it will automatically be stopped and rewound to the start unless the PlayMode is set to Loop.