视频比较功能优化

[williamfzc]

视频比较功能能够让stagesepx真正被用于功能校验上

[williamfzc]

现在的用法：

cutter = VideoCutter()
res = cutter.cut(video_path)
res1 = cutter.cut(another_video_path)

pprint.pprint(
    res.diff(res, frame_count=3)
)

输出（当前视频与另一个视频的阶段相似程度，例如，视频1的阶段0与视频2的阶段1的采样相似度是[0.8877483354832251, 0.8851640516034827, 0.8758058301476342]）：

{0: {0: [1.0, 1.0, 1.0],
     1: [0.8877483354832251, 0.8851640516034827, 0.8758058301476342]},
 1: {0: [0.8877483354832251, 0.8851640516034827, 0.8758058301476342],
     1: [1.0, 1.0, 1.0]}}