Function Wipe for vctrans vapoursynth Plugin

#
Wipe

The transition from Clip A to Clip B occurs by a wipe in the desired direction.

## trans.Wipe(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. A longer duration is preferable.
dir : 1 to 8. 1 : N, 8 : NW in a clockwise direction