* 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

Requires moving Atom rendering from DistributionWorker (where
`stream_entry.status` is already nil) to inline (where
`stream_entry.status.destroyed?` is true) and distributing that.

Unfortunately, such XML renderings can no longer be easily chained
together into one payload of n items.

* Pinned statuses

* yarn manage:translations

- Use unicode when selecting emoji through picker
- Convert shortcodes to unicode when storing text input server-side
- Do not convert shortcodes in JS anymore

* Fix boolean columns sometimes having a null value

* Fix wrong value being set instead of null

* Fix regression from #3842

Simplify the query by omitting all direct statuses. Private statuses
are allowed because they are from accounts we are following (so
by definition)

Resolves #3887 (alternative)

* Adjust test

The classes using Status.as_home_timeline, namely Feed and
PrecomputeFeedService are expected to filter direct statuses as
FanOutWriteService does, but their filtering were incomplete or missing.

This commit solves the problem by filtering direct statuses in
as_home_timeline as the other similar methods such as as_public_timeline
does.

* Default to nil for statuses.language

* Language detection defaults to nil instead of instance UI default

* Add a StatusFilter class to identify visibility of statuses by accounts

* Extract StatusThreadingConcern from Status

* Clarify purpose of checking for nil account

* Remove trailing whitespace in i18n mailers

* Use query methods instead of #present? on AR attributes

* Delegate Status#account_domain method

* Delegate Mention #account_username and #account_acct methods

* Introduce recent scope to Status and StreamEntry

Introduce recent scope to Status and StreamEntry as Account has.

* Cover AccountsController more in AccountsController

* Remove allowed_languages and add filtered_languages

* Use filtered_languages instead of allowed_languages

* Add buttons to block and unblock domain

* Relationship API now returns "domain_blocking" status for accounts,
rename "block entire domain" to "hide entire domain", fix unblocking domain,
do not block notifications from domain-blocked-but-followed people, do
not send Salmons to domain blocked users

* Add test

* Personal domain blocks shouldn't affect Salmon after all, since in this
direction of communication the control is very thin when it comes to
public stuff. Best stay consistent and not affect federation in this way

* Ignore followers and follow request from domain blocked folks,
ensure account domain blocks are not created for empty domain,
and avoid duplicates in validation

* Purge followers when blocking domain (without soft-blocks, since they
are useless here)

* Add tests, fix local timeline being empty when having any domain blocks

* Add <ostatus:conversation /> tag to Atom input/output

Only uses ref attribute (not href) because href would be
the alternate link that's always included also.

Creates new conversation for every non-reply status. Carries
over conversation for every reply. Keeps remote URIs verbatim,
generates local URIs on the fly like the rest of them.

* Conversation muting - prevents notifications that reference a conversation
(including replies, favourites, reblogs) from being created. API endpoints
/api/v1/statuses/:id/mute and /api/v1/statuses/:id/unmute

Currently no way to tell when a status/conversation is muted, so the web UI
only has a "disable notifications" button, doesn't work as a toggle

* Display "Dismiss notifications" on all statuses in notifications column, not just own

* Add "muted" as a boolean attribute on statuses JSON

For now always false on contained reblogs, since it's only relevant for
statuses returned from the notifications endpoint, which are not nested

Remove "Disable notifications" from detailed status view, since it's
only relevant in the notifications column

* Up max class length

* Remove pending test for conversation mute

* Add tests, clean up

* Rename to "mute conversation" and "unmute conversation"

* Raise validation error when trying to mute/unmute status without conversation

* Adding account domain blocks that filter notifications and public timelines

* Add tests for domain blocks in notifications, public timelines
Filter reblogs of blocked domains from home

* Add API for listing and creating account domain blocks

* API for creating/deleting domain blocks, tests for Status#ancestors
and Status#descendants, filter domain blocks from them

* Filter domains in streaming API

* Update account_domain_block_spec.rb

* Build query with arel node

* Add spec for current Status#permitted_for implementation

* Refactor status.rb

* Order by visibility to optimize query

possibly others when expected. Add some tests for it

* Add <ostatus:conversation /> tag to Atom input/output

Only uses ref attribute (not href) because href would be
the alternate link that's always included also.

Creates new conversation for every non-reply status. Carries
over conversation for every reply. Keeps remote URIs verbatim,
generates local URIs on the fly like the rest of them.

* Conversation muting - prevents notifications that reference a conversation
(including replies, favourites, reblogs) from being created. API endpoints
/api/v1/statuses/:id/mute and /api/v1/statuses/:id/unmute

Currently no way to tell when a status/conversation is muted, so the web UI
only has a "disable notifications" button, doesn't work as a toggle

* Display "Dismiss notifications" on all statuses in notifications column, not just own

* Add "muted" as a boolean attribute on statuses JSON

For now always false on contained reblogs, since it's only relevant for
statuses returned from the notifications endpoint, which are not nested

Remove "Disable notifications" from detailed status view, since it's
only relevant in the notifications column

* Up max class length

* Remove pending test for conversation mute

* Add tests, clean up

* Rename to "mute conversation" and "unmute conversation"

* Raise validation error when trying to mute/unmute status without conversation

* Add <ostatus:conversation /> tag to Atom input/output

Only uses ref attribute (not href) because href would be
the alternate link that's always included also.

Creates new conversation for every non-reply status. Carries
over conversation for every reply. Keeps remote URIs verbatim,
generates local URIs on the fly like the rest of them.

* Fix conversation migration

* More spec coverage for status before_create

* Prevent n+1 query when generating Atom with the new conversations

* Improve code style

* Remove redundant local variable

* add annotate to Gemfile

* rails g annotate:install

* configure annotate_models

* add schema info to models

* fix rubocop to add frozen_string_literal

* Naive approached to timeline filtering

* Convert allowed_languages into a db column

* Allow users to choose languages to see statuses in

* Style list items as two columns

* Add a hint to explain language filtering preference

* Add rough outline of coverage needed for public timeline

* Specs for visibility, replies, boosts

* Specs for silenced account

* Specs for local_only option

* Specs for blocks and mutes

* Add tentative spec around including other silenced account statuses

* Add with_public_visibility scope

* Add simple coverage for tag_timeline

* Tag timeline includes replies

* Replace tag.statuses with a tagged_with scope in tag timeline method

* Use with_public_visibility in tag timeline

* Extract common scope between public and tag timelines to method

* Extract local domain check to local_only scope

* Extract local_only check to starting scope method

* Move list of excluded from timeline account ids to account model

* Simplify excluded accounts list on account model

* Only join accounts when needed

* Rename method for account specific filtering

* Extract method for account exclusions

* Fix bug where silenced accounts were not including statuses from other silenced accounts

* DRY up filter application from account or no account

* timeline_scope can be private

* Add spec showing that account can find its excluded accounts ids

* Add spec which fails if local_only does not have a left outer join

* rubocop

* Clean up collapsible components

* Expose user Outboxes and AS2 representations of statuses

* Save work thus far.

* Fix bad merge.

* Save my work

* Clean up pagination.

* First test working.

* Add tests.

* Add Forbidden error template.

* Revert yarn.lock changes.

* Fix code style deviations and use localized instead of hardcoded English text.

* Add `required: true` option to foreign column

* Fixes NoMethodError

```
> Favourite.new.valid?
NoMethodError: undefined method `reblog?' for nil:NilClass
```

Checking reblog vs original status was happening in multiple places
across the app. For views, this logic was encapsulated in a helper
method named `proper_status` but in the other layers of the app, the
logic was duplicated.

Because the logic is used at all layers of the app, we extracted it into
a `Status#proper` method on the model and changed all uses of the logic
to use this method. There is now a single source of truth for this
condition.

We added test coverage to untested methods that got refactored.

adjusted to allow choosing it, yet

Redirect /:username to /users/:username
Redirect /:username/:id to /users/:username/updates/:id
Updated API documentation and sponsors

"whole known network" which is what public timeline used to be

Only domain blocks with suspend severity will block PuSH subscriptions
Silenced accounts should not appear in conversations unless followed