Hide banned artist pages from anonymous (logged out) users. Partial
revert of 6b066f2ca. Artists sometimes ask us to remove all their
information from the site, including their artist profile. It's easier
to hide their profile than to explain to Japanese artists that a) we're
under no obligation to remove their profile and b) we need to keep it to
maintain the ban on their content that they asked for.
Refactor to use accepts_nested_attributes_for instead of the notes
attribute to facilitate editing wikis on the artist edit page.
This fixes the notes attribute unintentionally showing up in the API.
This also changes it so that renaming an artist entry doesn't
automatically rename the corresponding wiki page. This had bad behavior
when there was a conflict between wiki pages (the wikis would be
silently merged, which usually isn't what you want). It also didn't warn
about wiki links being broken by renames.
* Replace the .category-N CSS classes on tags with .tag-type-N. Before
we were inconsistent about whether tag colors were indicated with
.category-N or .tag-type-N. Now it's always .tag-type-N.
* Fix various places to not use Tag.category_for. Tag.category_for does
one Redis call per tag lookup, which leads to N Redis calls on many
pages. This was inefficient because usually we either already had the
tags from the database, or we could fetch them easily.
Allow all users to view and edit artist entries and wiki pages belonging
to banned artists. There was little need to hide these pages from
Members, it was mainly to appease artists who didn't like us even
linking to their sites.
These restrictions also had multiple flaws:
* Banned artist information was still visible in the API.
* It was still possible to edit banned artists using the API.
* It was still possible for unprivileged users to revert banned
artist entries or wiki pages to previous versions.
* The restrictions were inconsistent: in various places they were
either Member-only, Gold-only, or Builder-only.
