Import resize.sh from stagestosaturn.git

https://github.com/foolip/stagestosaturn/blob/9d1166bf7e5841eb379cb094125d85075ca29633/resize.sh
Adapt resize.sh to local conditions

 * don't assume JPEG
 * increase quality to compensate for recompression
Crop the right/bottom border from images

Not all images had this, visual inspection was required.