* Tighten up illust id parsing to avoid misparsing ids from
non-illust urls (sketch urls and novel urls).
* Move id parsing tests from post_test.rb to sources/pixiv_test.rb.
* Drop support for touch.pixiv.net urls. These urls are no longer used
by Pixiv and aren't present as the source of any posts on Danbooru.
Bug: Uploading bad pixiv id images failed because the pixiv strategy
raised a BadIDError exception when the upload service checked for the
ugoira frame data.
* Rename `unique_id` to `tag_name`.
* Add `other_names` and `profile_urls` methods that sources can override
to provide extra names or urls when creating new artist entries.
* When creating an artist by clicking the '?' next to the artist tag in
the tag list, prefill the new artist form by finding the artist's last
upload and fetching its source data.
Previously we filled the urls with the source of the artist's last
upload, which was wrong because it was usually a direct image URL (#3078).
* Fix the other names field not escaping spaces within names to underscores.
* Fix the other names field being potentially prefilled with duplicate names.
* Normalize spaces to underscores when saving other names. Preserve case
since case can be significant.
* Fix WikiPage#other_names_include to search case-insensitively (note:
this prevents using the index).
* Fix sources to return the raw tags in `#tags` and the normalized tags
in `#normalized_tags`. The normalized tags are the tags that will be
matched against other names.
* Don't fail on urls that don't contain the project id (direct image urls).
* Don't fail when the work is deleted.
* Parse artist name from url when possible. This way the artist finder works on bad_artstation_id posts.
* Set canonical source url to `https://artist.artstation.com/projects/12345` instead of
`https://www.artstation.com/artwork/1235` (this way we preserve the artist name).
* Cache api call.
* Include api call results in /source.json.
Fix sources choosing the wrong strategy when the referer belongs to a
different site (for example, when uploading a twitter post with a pixiv
referer).
* Fix `match?` to only consider the main url, not the referer.
* Change `match?` to match against a list of domains given by the `domains` method.
* Change `match?` to an instance method.
Derive the artist name / profile url / page url from the source URLs when
the API response is unavailable because the Tumblr post was deleted.
This fixes the artist finder to work on bad_tumblr_id posts.
If the yande.re or konachan.com post has a source from a supported site,
for example Pixiv or Twitter, then delegate the artist and commentary
lookup to that substrategy.
Only do this for sources from recognized sites, not the null strategy.
