If the input text is blank after preparation (only mention, or
only URL, or empty as in a media post), then use nil as language,
since it's OK to show to everyone.
Otherwise, always fall back to the server's default locale
* Scrub text of html before detecting language.
* Detect language on statuses coming from activitypub.
* Fix rubocop comments.
* Remove custom emoji from text before language detection
* Fix language filter codes
CLD3 returns BCP-47 language identifier, filter settings expect
identifiers in the ISO 639-1 format. Convert between formats,
and exclude duplicate languages from filter choices (zh-CN->zh)
* Fix zh name
* Add failing specs for hashtag and username extraction in language detector
* Remove usernames and hashtags from text before language detection
* Handle multiple instances of special case, and reduce whitespace
Eugen Rochko
Jeong Arm
Renato "Lond" Cerqueira
Akihiko Odaki
Matt Jankowski