add assets, fix coloring, update readme and art tools

See !11329 (closed) for previous discussion.

I remade the request because I fucked up my repository.

Vector art for catgirl mod did not work:

• Only one ear displayed
• Ears and tail colors do not match descriptions
• No distinct art for face, and logic would never vary facial appearance

No art for elf ears

A couple examples:

Note how the subtle shading from the old cat ears is lost, but now at least the color matches.

artTools readme lacked a few bits of information

normalize_svg.py was updated to handle a couple new color definitions

marked this merge request as draft

marked this merge request as ready

@Pregmodder should be good to go now.

mentioned in commit 4eda8562

merged