Lossless file size reduction of all images.

Because it is a little over the top to use 3*8 bits/pixel (RBG)
or even 4*8 bps (RGBA) to store images with only 2 or 4 colors.

And the webserver will be happy to serve only 576.289 (50.8%)
instead of 1.133.581 bytes.

OptiPNG is nice!