nuke 'shiny hair'

BUR #13706 has been approved by @evazion.

mass update shiny_hair shiny -> -shiny
nuke shiny_hair
deprecate shiny_hair

The mass update won't remove shiny from posts with other shiny-implying tags (shiny clothes or shiny skin). There are under 6,000 posts that have shiny outside of these three implying tags (e.g. shiny doorknob).

Shiny hair applies to nearly every post on the site, but is only tagged on 127k posts. Compare topic #21159.
It's not an indicator of hair being shinier than normal. Any shinier and it's usually just comically radiant blonde hair, glowing hair, or wet hair.

Removed the line unimply shiny_hair -> shiny since it doesn't exist anymore.

For exceptionally shiny hair we could have a special tag for them, but yeah, the tag currently is utter trash.

This is yet another tag that only exists because uploaders figured out it was a "free" tag they could add to every post. Shiny hair is a standard part of the anime art style, the same way big eyes and tiny noses are. This is tantamount to tagging every post with big eyes because anime characters have big eyes.

The bulk update request #13706 (forum #227781) has been approved by @evazion.