message: Fix MatToUIImage method crash when the step is not equal to cols * elemSize()
diff: @@ -53,7 +53,7 @@ void UIImageToMat(const UIImage* image, cv::Mat& m, bool alphaExist);
  UIImage* MatToUIImage(const cv::Mat& image) {
  NSData *data = [NSData dataWithBytes:image.data
  - length:image.elemSize()*image.total()];
  + length:image.step.p[0] * image.rows];
  CGColorSpaceRef colorSpace;
  @@ -73,7 +73,7 @@ UIImage* MatToUIImage(const cv::Mat& image) {
  // Creating CGImage from cv::Mat
  CGImageRef imageRef = CGImageCreate(image.cols,
  image.rows,
  - 8,
  + 8 * image.elemSize1(),
  8 * image.elemSize(),
  image.step.p[0],
  colorSpace,
  