Gets the shortest angle between
Both angles must be in the range -180 to 180, which is the same clamped
sprite.angle uses, so you can pass in two sprite angles to
this method and get the shortest angle back between the two of them.
The angle returned will be in the same range. If the returned angle is greater than 0 then it's a counter-clockwise rotation, if < 0 then it's a clockwise rotation.
The first angle in the range -180 to 180.
The second angle in the range -180 to 180.
The shortest angle, in degrees. If greater than zero it's a counter-clockwise rotation.