* Make PreviewCard records reuseable between statuses

**Warning!** Migration truncates preview_cards tablec

* Allow a wider thumbnail for link preview, display it in horizontal layout (#4648)

* Delete preview cards files before truncating

* Rename old table instead of truncating it

* Add mastodon:maintenance:remove_deprecated_preview_cards

* Ignore deprecated_preview_cards in schema definition

* Fix null behaviour

* ActivityPub migration procedure

Once one account is detected as going from OStatus to ActivityPub,
invalidate WebFinger cache for other accounts from the same domain

* Unsubscribe from PuSH updates once we receive an ActivityPub payload

* Re-subscribe to PuSH unless already unsubscribed, regardless of protocol

* Move clean up of unconfirmed users to sidekiq-scheduler

* mastodon:daily is now deprecated

* Check table existence on prepare_for_foreign_keys

* Remove trailing whitespace

* Add Rake task for generate VAPID key

* edit config/initializers/vapid.rb

Can be filtered by a specific domain
Resolves #2292

* Redesign the landing page, mount public timeline on it

* Adjust the standalone mounted component to the lacking of router

* Adjust auth layout pages to new design

* Fix tests

* Standalone public timeline polling every 5 seconds

* Remove now obsolete translations

* Add responsive design for new landing page

* Address reviews

* Add floating clouds behind frontpage form

* Use access token from public page when available

* Fix mentions and hashtags links, cursor on status content in standalone mode

* Add footer link to source code

* Fix errors on pages that don't embed the component, use classnames

* Fix tests

* Change anonymous autoPlayGif default to false

* When gif autoplay is disabled, hover to play

* Add option to hide the timeline preview

* Slightly improve alt layout

* Add elephant friend to new frontpage

* Display "back to mastodon" in place of "login" when logged in on frontpage

* Change polling time to 3s

* Add rake task to prepare database for foreign keys introduced by #3562

* Fix typo

* Do not delete OAuth values where NULL values may be permitted

* Fix typo

sidekiq-scheduler jobs

Resolves #2495

* Fix #2473 - Use sidekiq scheduler to refresh PuSH subscriptions instead of cron

Fix an issue where / in domain would raise exception in TagManager#normalize_domain

PuSH subscriptions refresh done in a round-robin way to avoid hammering a single
server's hub in sequence. Correct handling of failures/retries through Sidekiq (see
also #2613). Optimize Account#with_followers scope. Also, since subscriptions
are now delegated to Sidekiq jobs, an uncaught exception will not stop the entire
refreshing operation halfway through

Fix #2702 - Correct user agent header on outgoing http requests

* Add test for SubscribeService

* Extract #expiring_accounts into method

* Make mastodon:push:refresh no-op

* Queues are now defined in sidekiq.yml

* Queues are now in sidekiq.yml

* Remove best_in_place

* Replace best_in_place usage with rails helpers

* Move admin/settings#index to #edit action

* Remove click_to__edit from i18n

* downgrade rubocop 0.48.1 => 0.46.0

* exclude vendor/**/* from rubocop target files

* add frozen_string_literal comment line

* fix percent literal delimited by ( and )

* fix alignment

* remove comment disabling unknown cop

Follow-up to #2599. When a domain block with `reject_media` is
added or `rake mastodon:media:remove_remote` is invoked, mastodon
deletes the locally cached attachments and avatars but does not
reflect that change in the database, causing the `file` fields to
still have values. This change persists the deletion in the
database and sets the attachment type to unknown.

This also introduces a one-off rake task that sets all attachments
without a local file to the "unknown" type. The upgrade notes for
the next release should contain a post-upgrade step with
`rake mastodon:media:set_unknown`.

* Adds logging for daily tasks.

* Fixes Code Climate issues in #2438.

* Remove unused method #set_counters_maps from api controller

* Remove unused method #set_account_counters_maps from api controller

* Remove unused method Account#followers_domains

* Remove unused User.prolific scope

* Add mastodon:users:admins task to list all admin emails

* Use interpolated query style in Account.triadic_closures

* Coverage for Account.triadic_closures

Also improve efficiency of the mastodon:maintenance:add_static_avatars task

* Unite all mandatory rake tasks in mastodon:daily
Add mastodon:media:remove_remote task
Make mastodon:maintenance:add_static_avatars more resilient to exceptions

* Fix typo in task description

Before it cleared out user records only (e-mail, password) without
freeing up the associated username (account record). Furthermore, since
these records have no dependent records (due to no user activity)
they can be deleted quickly with delete_all instead of destroy

* Add tasks for open/close registration

* Code climate style fix

* Use true instead of string 'true'

* add task in order to delete unconfirmed user

* change 7 days to 2

* When avatar/header are GIF, generate static versions.
Account API returns "avatar"/"avatar_static", "header"/"header_static"
Static version is the same as original for other cases
Web UI de-animates avatars in toots, lists of users

Fix #441, fix #596, prerequisite for #1064

* Fix JS test

* Add rake task to generate static avatars/headers from GIF ones, add test

* Adds task to confirm user by email.

* Adds documentation for manual confirmation.

redis-backed "mentions" timeline as redundant (given notifications)

(without avatar). Also improved search position of exact matches

to the API

respect hub.lease_seconds (fix #46)