Lossless optimization of png image files, using `pngslim` and other tools.
Documentation only artwork (distributed outside a program):
- Slimmed 26.7 KiB (~22.2 KiB kpacked), average ~40% saving.
git-svn-id: svn://kolibrios.org@10014 a494cfbc-eb01-0410-851d-a64ba20cac60
