Function Sprite for vctrans vapoursynth Plugin

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Sprite

The transition from Clip A to Clip B occurs as a rotating Sprite A frame rotating away with B frame coming in.

## trans.Sprite(clip, clipb clip[, float overlap = 1.0 ][, int dir = 1] )

Parameter description:
clip : A clip. Constant format.
clipb : B clip. Must have identical format of A clip
overlap : transition time length in seconds. Floating point. Must correspond to at least 8 frames.
dir :Rotation direction 1 to 4. 1:N (up) 2: E (right) 3: S (down) 4 : W (left)
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