* 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

Each of mute, favourite, reblog has been updated to:

- Have a separate controller with just a create and destroy action
- Preserve historical route names to not break the API
- Mild refactoring to break up long methods

* Add specs for api statuses routes

* Update favourited_by and reblogged_by api routes

* Move methods into new controllers

* Use load_accounts methods to simplify index actions

* Clean up load_accounts methods

* Clean up link header generation

* Check for link headers in specs

* Remove unused actions from api/v1/statuses controller

* Remove specs for moved actions

* Move ApiController to Api/BaseController

* API controllers inherit from Api::BaseController

* Add coverage for various error cases in api/base controller

* Add status destroy authorization to policy

* Create explicit unreblog status authorization

This commit fixes a regression in commit
f554807563.

The regressions are introduced at commit
f554807563 by me (Akihiko Odaki)

* 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

duplicates. Web UI regenerates UUID for that header every time the compose
form is changed or successfully submitted

Also, fix Farsi i18n overwriting the English one

* Make /api/v1/timelines/public and /api/v1/timelines/tag/:id public
Fix #1156 - respect query params when generating pagination links in API

* Apply pagination fix to more APIs

Using catch statement in api_controller.rb to catch NotPermitted
Exception, and render error message

Moved validation to services/post_status_service.rb

Federate spoiler_text using warning attribute on <content /> instead of a <category term="spoiler" />
Clean up schema file from accidental development migrations

now return empty hash instead of throwing a 404 error. When following,
merge into timeline will filter statuses

Filters out hidden stream entries from Atom feed
Blocks now generate hidden stream entries, can be used to federate blocks
Private statuses cannot be reblogged (generates generic 422 error for now)
POST /api/v1/statuses now takes visibility=(public|unlisted|private) param instead of unlisted boolean
Statuses JSON now contains visibility=(public|unlisted|private) field

Fix #233, fix #268

account results

resources that require a user context vs those that don't (such as public timeline)

/api/v1/statuses/public   -> /api/v1/timelines/public
/api/v1/statuses/home     -> /api/v1/timelines/home
/api/v1/statuses/mentions -> /api/v1/timelines/mentions
/api/v1/statuses/tag/:tag -> /api/v1/timelines/tag/:tag

to the API