some improvement
从YUV中抽取ROI的Python脚本
added U V support for MB comparision
Added .gitignore
Added a example conf file for cut_yuv
Added a Python script for pad YUV Left and Top, Now only with all 0
pad_yuv增加输出正处理的帧数, 处理方式小改以增加速度, 配置文件修改.

1, pad_yuv运行的时候输出正在跑的帧数.
2, 原来的pad_yuv运行的时候对每行都算一次 "\0"*TopLeftX,
   改成了只在最开始的时候算一次
3, 配置文件源YUV改成了720P
Added Command Line -c to specify conf file