This reverts commit e83d07ea7b.
It was worth a try, but unfortunately it seems that once
someone sets tools in a Pixiv upload, they become defaults and
are applied to all of their subsequent uploads, so we get some
posts with two or three different digital tags.
Fixes an exception when attempting to upload a Pixiv image from a
deleted work. The download strategy tries to fetch the source data in
the course of rewriting the URL, which fails if the work has been
deleted from Pixiv.
Raise a BadIDError and leave the URL as-is (don't rewrite it).
Fixes an "incompatible character encodings: UTF-8 and ASCII-8BIT"
exception when uploading a deleted Pixiv post.
Caused by the Pixiv API error message not having the encoding set to UTF-8.
* Only suggest the Danbooru tag with the same name if there is no
matching wiki other name. Example: if we have the Pixiv tag `Fate` and
the Danbooru tag `fate_(series)` with other name `fate`, suggest that,
not the Danbooru tag `fate`.
* Don't suggest tags that are empty or whose wiki is deleted.
* Only split tags on "/" if there are no other matches, and only for Pixiv.
* For Pixiv, only include traditional media tags in tag list, not digital media (Photoshop, SAI).
* Add some tests.
