Fixes #5188

* Fix order of paginated accounts in FollowerDomainsController

Unordered pagination could result in unexpected behavior.

* Cover Settings::FollowerDomainsController more

* Upgrade to React 16.0.0

* Disable some uncritical tests while chai-enzyme remains incompatible

- A successful delivery cancels it out
- An incoming delivery from account of the inbox cancels it out

Blaze it

* Fix #117 - Add ability to specify alternative text for media attachments

- POST /api/v1/media accepts `description` straight away
- PUT /api/v1/media/:id to update `description` (only for unattached ones)
- Serialized as `name` of Document object in ActivityPub
- Uploads form adjusted for better performance and description input

* Add tests

* Change undo button blend mode to difference

A new rake task emojis:generate downloads a full list of valid
unicode sequences from unicode.org and checks it against existing
Twemoji files, finally generating a map from each sequence to the
existing file (e.g. when there's multiple ways an emoji can be
expressed). The map is dumped into app/javascript/mastodon/emoji_map.json

That file is loaded by emojione_light.js (now a misnomer) which
decorates it further with shortcodes taken from emoji-mart's index.

* Add emoji autosuggest

Some credit goes to glitch-soc/mastodon#149

* Remove server-side shortcode->unicode conversion

* Insert shortcode when suggestion is custom emoji

* Remove remnant of server-side emojis

* Update style of autosuggestions

* Fix wrong emoji filenames generated in autosuggest item

* Do not lazy load emoji picker, as that no longer works

* Fix custom emoji autosuggest

* Fix multiple "Custom" categories getting added to emoji index, only add once

* Switch from EmojiOne to Twemoji, different emoji picker

* Make emoji-mart use a local spritesheet

* Fix emojify test

* yarn manage:translations

* Make dropdowns render into portal, expand animation

* Improve actions modal style

* Fix JavaScript interface with long IDs

Somewhat predictably, the JS interface handled IDs as numbers, which in
JS are IEEE double-precision floats. This loses some precision when
working with numbers as large as those generated by the new ID scheme,
so we instead handle them here as strings. This is relatively simple,
and doesn't appear to have caused any problems, but should definitely
be tested more thoroughly than the built-in tests. Several days of use
appear to support this working properly.

BREAKING CHANGE:

The major(!) change here is that IDs are now returned as strings by the
REST endpoints, rather than as integers. In practice, relatively few
changes were required to make the existing JS UI work with this change,
but it will likely hit API clients pretty hard: it's an entirely
different type to consume. (The one API client I tested, Tusky, handles
this with no problems, however.)

Twitter ran into this issue when introducing Snowflake IDs, and decided
to instead introduce an `id_str` field in JSON responses. I have opted
to *not* do that, and instead force all IDs to 64-bit integers
represented by strings in one go. (I believe Twitter exacerbated their
problem by rolling out the changes three times: once for statuses, once
for DMs, and once for user IDs, as well as by leaving an integer ID
value in JSON. As they said, "If you’re using the `id` field with JSON
in a Javascript-related language, there is a very high likelihood that
the integers will be silently munged by Javascript interpreters. In most
cases, this will result in behavior such as being unable to load or
delete a specific direct message, because the ID you're sending to the
API is different than the actual identifier associated with the
message." [1]) However, given that this is a significant change for API
users, alternatives or a transition time may be appropriate.

1: https://blog.twitter.com/developer/en_us/a/2011/direct-messages-going-snowflake-on-sep-30-2011.html

* Additional fixes for stringified IDs in JSON

These should be the last two. These were identified using eslint to try
to identify any plain casts to JavaScript numbers. (Some such casts are
legitimate, but these were not.)

Adding the following to .eslintrc.yml will identify casts to numbers:

~~~
  no-restricted-syntax:
  - warn
  - selector: UnaryExpression[operator='+'] > :not(Literal)
    message: Avoid the use of unary +
  - selector: CallExpression[callee.name='Number']
    message: Casting with Number() may coerce string IDs to numbers
~~~

The remaining three casts appear legitimate: two casts to array indices,
one in a server to turn an environment variable into a number.

* Back out RelationshipsController Change

This was made to make a test a bit less flakey, but has nothing to
do with this branch.

* Change internal streaming payloads to stringified IDs as well

Per
https://github.com/tootsuite/mastodon/pull/5019#issuecomment-330736452
we need these changes to send deleted status IDs as strings, not
integers.

* Custom emoji

- In OStatus: `<link rel="emoji" name="coolcat" href="http://..." />`
- In ActivityPub: `{ type: "Emoji", name: ":coolcat:", href: "http://..." }`
- In REST API: Status object includes `emojis` array (`shortcode`, `url`)
- Domain blocks with reject media stop emojis
- Emoji file up to 50KB
- Web UI handles custom emojis
- Static pages render custom emojis as `<img />` tags

Side effects:

- Undo #4500 optimization, as I needed to modify it to restore
  shortcode handling in emojify()
- Formatter#plaintext should now make sure stripped out line-breaks
  and paragraphs are replaced with newlines

* Fix emoji at the start not being converted

* Fix an error when actor json couldn't be fetched in ResolveRemoteAccountService

* Add specs

* Improve OpenGraph tags for about pages

* Add thumbnail admin setting

* Fix error

* Fix up

* Fix ActivityPub handling of replies when LOCAL_DOMAIN ≠ WEB_DOMAIN (#4895)

For all intents and purposes, `local_url?` is used to check if an URL refers
to the Web UI or the various API endpoints of the local instances. Those things
reside on `WEB_DOMAIN` and not `LOCAL_DOMAIN`.

* Change local_url? spec, as all URLs handled by Mastodon are based on WEB_DOMAIN

- Return all images as og:image
- Return videos as og:image (preview) and og:video
- Return profile:username on profiles

When a new user confirms their e-mail, bootstrap their home timeline
by automatically following a set of accounts. By default, all local
admin accounts (that are unlocked). Can be customized by new admin
setting (comma-separated usernames, local and unlocked only)

In before, the method uses stream_entry id as status id, so replied status was wrongly selected.

This PR uses StatusFinder which was introduced with `Api::Web::EmbedsController`.

* Fix language filter codes

CLD3 returns BCP-47 language identifier, filter settings expect
identifiers in the ISO 639-1 format. Convert between formats,
and exclude duplicate languages from filter choices (zh-CN->zh)

* Fix zh name

* Decouple Status#local? from uri being nil

* Replace on-the-fly URI generation with stored URIs

- Generate URI in after_save hook for local statuses
- Use static value in TagManager when available, fallback to tag format
- Make TagManager use ActivityPub::TagManager to understand new format
- Adjust tests

* Use other heuristic for locality of old statuses, do not perform long query

* Exclude tombstone stream entries from Atom feed

* Prevent nil statuses from landing in Pubsubhubbub::DistributionWorker

* Fix URI not being saved (#4818)

* Add more specs for Status

* Save generated uri immediately

and also fix method order to minimize diff.

* Fix alternate HTML URL in Atom

* Fix tests

* Remove not-null constraint from statuses migration to speed it up