static BufferedImage mergeBufferedImagesHorizontally(BufferedImage... images) {
  ret mergeBufferedImagesHorizontally(toList(images));
}

static BufferedImage mergeBufferedImagesHorizontally(L<BufferedImage> images) {
  int spacing = imageMergeSpacing();
  RGB spaceColor = new RGB(0.9f);
  int w = intSum(images, "width")+(l(images)-1)*spacing, h = intMax(images, "height");
  BufferedImage out = newBufferedImage(w, h, spaceColor);
  int x = 0;
  for i over images: {
    BufferedImage img = images.get(i);
    int y = (h-img.getHeight())/2;
    copyBufferedImage(img, out, x, y);
    x += img.getWidth() + spacing;
  }
  ret out;
}