通过一个polygon裁切栅格图像，可按照这个polygon的外边裁切，也可按其最小外包矩形裁切-By cutting a polygon raster image, you can follow the outside of the polygon cut, in accordance with the minimum bounding cutting

对任意多边形最小面积的外包矩形求解，求解的结果为该矩形的四个顶点坐标(Minimum circumscribed rectangle of polygon)