Update to wagtail-2.10:

* Added Django 3.1 support (Matt Westcott, Karl Hobley)
* Removed support for Python 3.5
* Implemented configurable moderation workflow (Jacob Topp-Mugglestone, Karl Hobley, Matt Westcott, Dan Braghis)
* Implemented phrase searching and structured search query expressions (Karl Hobley)
* Add ability to import redirects from an uploaded file (CSV, TSV, XLS, and XLSX) (Martin Sandström)
* Added `webpquality` and `format-webp-lossless` image filters and `WAGTAILIMAGES_WEBP_QUALITY` setting (Nikolay Lukyanov)
* Reorganised Dockerfile in project template to follow best practices (Tomasz Knapik, Jannik Wempe)
* Added filtering to locked pages report (Karl Hobley)
* Adds ability to view a group's users via standalone admin URL and a link to this on the group edit view (Karran Besen)
* Redirect to previous url when deleting/copying/unpublish a page and modify this url via the relevant hooks (Ascani Carlo)
* Added `next_url` keyword argument on `register_page_listing_buttons` and `register_page_listing_more_buttons` hooks (Ascani Carlo, Matt Westcott, LB (Ben Johnston))
* `AbstractEmailForm` will use `SHORT_DATETIME_FORMAT` and `SHORT_DATE_FORMAT` Django settings to format date/time values in email (Haydn Greatnews)
* `AbstractEmailForm` now has a separate method (`render_email`) to build up email content on submission emails (Haydn Greatnews)
* Add `pre_page_move` and `post_page_move` signals (Andy Babic)
* Add ability to sort search promotions on listing page (Chris Ranjana, LB (Ben Johnston))
* Upgrade internal JS tooling; Node v10, Gulp v4 & Jest v23 (Jim Jazwiecki, Kim LaRocca, Thibaud Colas)
* Add `after_publish_page`, `before_publish_page`, `after_unpublish_page` & `before_unpublish_page` hooks (Jonatas Baldin, Coen van der Kamp)
* Add convenience `page_url` shortcut to improve how page URLs can be accessed from site settings in Django templates (Andy Babic)
* Show more granular error messages from Pillow when uploading images (Rick van Hattem)
* Add ordering to `Site` object, so that index page and `Site` switcher will be sorted consistently (Coen van der Kamp, Tim Leguijt)
* Add Reddit to oEmbed provider list (Luke Hardwick)
* Add ability to replace the default Wagtail logo in the userbar, via `branding_logo` block (Meteor0id)
* Remove sticky footer on small devices, so that content is not blocked and more easily editable (Saeed Tahmasebi)
* Add `alt` property to `ImageRenditionField` api representation (Liam Mullens)
* Add `purge_revisions` management command to purge old page revisions (Jacob Topp-Mugglestone, Tom Dyson)
* Render the Wagtail User Bar on non `Page` views (Caitlin White, Coen van der Kamp)
* Add ability to define `form_classname` on `ListBlock` & `StreamBlock` (LB (Ben Johnston))
* Add documentation about how to use `Rustface` for image feature detection (Neal Todd)
* Improve performance of public/not_public queries in `PageQuerySet` (Timothy Bautista)
* Add `add_redirect` static method to `Redirect` class for programmatic redirect creation (Brylie Christopher Oxley, Lacey Williams Henschel)
* Add reference documentation for `wagtail.contrib.redirects` (LB (Ben Johnston))
* `bulk_delete` page permission is no longer required to move pages, even if those pages have children (Robert Rollins, LB (Ben Johnston))
* Add `after_edit_snippet`, `after_create_snippet` and `after_delete_snippet` hooks and documentation (Kalob Taulien)
* Improve performance of empty search results by avoiding downloading the entire search index in these scenarios (Lars van de Kerkhof, Coen van der Kamp)
* Replace `gulp-sass` with `gulp-dart-sass` to improve core development across different platforms (Thibaud Colas)
* Add SVG icons to resolve accessibility and customisation issues and start using them in a subset of Wagtail's admin (Coen van der Kamp, Scott Cranfill, Thibaud Colas, Dan Braghis)
* Switch userbar and header H1s to use SVG icons (Coen van der Kamp)
* Remove markup around rich text rendering by default, provide a way to use old behaviour via `wagtail.contrib.legacy.richtext` (Coen van der Kamp, Dan Braghis)
* Apply title length normalisation to improve ranking on PostgreSQL search (Karl Hobley)
* Add `WAGTAIL_TIME_FORMAT` setting (Jacob Topp-Mugglestone)
* Allow omitting the default editor from `WAGTAILADMIN_RICH_TEXT_EDITORS` (Gassan Gousseinov)
* Disable password auto-completion on user creation form (Samir Shah)
* Upgrade jQuery to version 3.5.1 to reduce penetration testing false positives (Matt Westcott)
* Add ability to extend `EditHandler` without a children attribute (Seb Brown)
* `Page.objects.specific` now gracefully handles pages with missing specific records (Andy Babic)
* StreamField 'add' buttons are now disabled when maximum count is reached (Max Gabrielsson)
* Use underscores for form builder field names to allow use as template variables (Ashia Zawaduk, LB (Ben Johnston))
* Deprecate use of unidecode within form builder field names (Michael van Tellingen, LB (Ben Johnston))
* Improve error feedback when editing a page with a missing model class (Andy Babic)
* Change Wagtail tabs implementation to only allow slug-formatted tab identifiers, reducing false positives from security audits (Matt Westcott)
* Add skip link for keyboard users to bypass Wagtail navigation in the admin (Martin Coote)
* Ensure errors during Postgres search indexing are left uncaught to assist troubleshooting (Karl Hobley)
* Add ability to edit images and embeds in rich text editor (Maylon Pedroso, Samuel Mendes, Gabriel Peracio)
* Fix: Support IPv6 domain (Alex Gleason, Coen van der Kamp)
* Fix: Ensure link to add a new user works when no users are visible in the users list (LB (Ben Johnston))
* Fix: `AbstractEmailForm` saved submission fields are now aligned with the email content fields, `form.cleaned_data` will be used instead of `form.fields` (Haydn Greatnews)
* Fix: Removed ARIA `role="table"` from TableBlock output (Thibaud Colas)
* Fix: Set Cache-Control header to prevent page preview responses from being cached (Tomas Walch)
* Fix: Accept unicode characters in slugs on the "copy page" form (François Poulain)
* Fix: Remove top padding when `FieldRowPanel` is used inside a `MultiFieldPanel` (Jérôme Lebleu)
* Fix: Add Wagtail User Bar back to page previews and ensure moderation actions are available (Coen van der Kamp)
* Fix: Resolve issue where queryset annotations were lost (e.g. `.annotate_score()`) when using specific models in page query (Dan Bentley)
* Fix: Prevent date/time picker from losing an hour on losing focus when 12-hour times are in use (Jacob Topp-Mugglestone)
* Fix: Strip out HTML tags from `RichTextField` & `RichTextBlock` search index content (Timothy Bautista)
* Fix: Avoid using null on string `Site.site_name` blank values to avoid different values for no name (Coen van der Kamp)
* Fix: Fix deprecation warnings on Elasticsearch 7 (Yngve Høiseth)
* Fix: Remove use of Node.forEach for IE 11 compatibility in admin menu items (Thibaud Colas)
* Fix: Fix incorrect method name in SiteMiddleware deprecation warning (LB (Ben Johnston))
* Fix: `wagtail.contrib.sitemaps` no longer depends on SiteMiddleware (Matt Westcott)
* Fix: Purge image renditions cache when renditions are deleted (Pascal Widdershoven, Matt Westcott)
* Fix: Image / document forms now display non-field errors such as `unique_together` constraints (Matt Westcott)
* Fix: Make "Site" chooser in site settings translateable (Andreas Bernacca)
* Fix: Add missing dropdown icons to image upload, document upload, and site settings screens (Andreas Bernacca)
* Fix: Prevent snippets’ bulk delete button from being present for screen reader users when it’s absent for sighted users (LB (Ben Johnston))
* Fix: Fix group permission checkboxes not being clickable in IE11 (LB (Ben Johnston))

(joerg)