Use -quality 90 in resize.sh

ImageMagick will default to the original quality, which is higher
than needed for viewing purposes. This cuts EPUB size in half.
Add higher resolution scans for chapter 8

Source: https://ia600308.us.archive.org/6/items/stagestosaturnte00bilsrich/stagestosaturnte00bilsrich_raw_jp2.zip
Add higher resolution scans for chapter 9

Source: https://ia600308.us.archive.org/6/items/stagestosaturnte00bilsrich/stagestosaturnte00bilsrich_raw_jp2.zip