测试sift特征点，并且在图片中显示出来。直接在sift源码上修改的，将提取特征点部分和匹配部分分开了，这部分是提取特征点。在vs2010上可运行，需要配置opencv-Test sift feature points and displayed in the picture. On sift modified source code directly, the feature points are extracted portion and mating portion separated,