Additions
- [booru] implement generalized extractors for `*booru` and `moebooru` sites
- add support for sakugabooru.com ([1136](https://github.com/mikf/gallery-dl/issues/1136))
- add support for lolibooru.moe ([1050](https://github.com/mikf/gallery-dl/issues/1050))
- provide formattable `date` metadata fields ([1138](https://github.com/mikf/gallery-dl/issues/1138))
- [postprocessor:metadata] add `event` and `filename` options ([315](https://github.com/mikf/gallery-dl/issues/315), [#866](https://github.com/mikf/gallery-dl/issues/866), [#984](https://github.com/mikf/gallery-dl/issues/984))
- [postprocessor:exec] add `event` option ([992](https://github.com/mikf/gallery-dl/issues/992))
Changes
- [flickr] update default directories and improve metadata consistency ([828](https://github.com/mikf/gallery-dl/issues/828))
- [sankaku] use API endpoints from `beta.sankakucomplex.com`
- [downloader:http] improve filename extension handling ([776](https://github.com/mikf/gallery-dl/issues/776))
- replace all JPEG filename extensions with `jpg` by default
Fixes
- [hentainexus] fix extraction ([1166](https://github.com/mikf/gallery-dl/issues/1166))
- [instagram] rewrite ([1113](https://github.com/mikf/gallery-dl/issues/1113), [#1122](https://github.com/mikf/gallery-dl/issues/1122), [#1128](https://github.com/mikf/gallery-dl/issues/1128), [#1130](https://github.com/mikf/gallery-dl/issues/1130), [#1149](https://github.com/mikf/gallery-dl/issues/1149))
- [mangadex] handle external chapters ([1154](https://github.com/mikf/gallery-dl/issues/1154))
- [nozomi] handle empty `date` fields ([1163](https://github.com/mikf/gallery-dl/issues/1163))
- [paheal] create directory for each post ([1147](https://github.com/mikf/gallery-dl/issues/1147))
- [piczel] update API URLs
- [twitter] update image URL format ([1145](https://github.com/mikf/gallery-dl/issues/1145))
- [twitter] improve `x-csrf-token` header handling ([1170](https://github.com/mikf/gallery-dl/issues/1170))
- [webtoons] update `ageGate` cookies
Removals
- [sankaku] remove login support