* Add "general" rating.
* Rename "safe" rating to "sensitive".
* Change safe mode to include both rating:s and rating:g.
* Treat rating:safe as a synonym for rating:sensitive.
* Link "howto:rate" in the post edit form.
For small thumbnails, use 180x180 thumbnails scaled down to 150x150.
This is so we can get rid of 150x150 images and just use 180x180 for
both small and medium size thumbnails.
Also fix RSS feeds, XML sitemaps, and Discord embeds to use 360x360
thumbnails instead of 150x150 thumbnails.
Rework sitemaps to provide more coverage of the site. We want every
important page on the site - including every post, tag, and wiki page -
to be indexed by Google. We do this by generating sitemaps and sitemap
indexes that contain links to every important page on the site.
