* Fix #2102 - Implement hotkeys

Hotkeys on status list:

- r to reply
- m to mention author
- f to favourite
- b to boost
- enter to open status
- p to open author's profile
- up or k to move up in the list
- down or j to move down in the list
- 1-9 to focus a status in one of the columns
- n to focus the compose textarea
- alt+n to start a brand new toot
- backspace to navigate back

* Add navigational hotkeys

The key g followed by:

- s: start
- h: home
- n: notifications
- l: local timeline
- t: federated timeline
- f: favourites
- u: own profile
- p: pinned toots
- b: blocked users
- m: muted users

* Add hotkey for focusing search, make escape un-focus compose/search

* Fix focusing notifications column, fix hotkeys in compose textarea

Use the non-animated version in web UI, but return both in API

* Use own, shorter relative timestamps

* Add acct to title tooltip of display name in statuses

* Improve i18n of the relative times

* Add pagination in media modal

* Change array name

* Add an element class

* Avoid nested class

* Pull out the active class

* Use map instead of forEach

* Remove parentheses

* yarn manage:translations

* Add Japanese translations for #5170

* Add Japanese translations for #5123

* Add Japanese translations for #5046

* Add Japanese translations for #5099

* Add Japanese translations for #5161

* "項目" -> "絵文字"

aria-label contained body of status with content warning, which should be
hidden by default. Remove the label for the case and other cases due to
consistency.

* When muting, clear web UI like for blocks

* Fix style issue

* Update translation files

Signed-off-by: Marcin Mikołajczak <me@m4sk.in>

* i18n: Update Polish translation

Signed-off-by: Marcin Mikołajczak <me@m4sk.in>

* Toggle contain:strict on fullscreen

* Fix scss lint issue

* fix scss whitespace lint issue

* Improve privacy dropdown, remove react-simple-dropdown dependency

* Animate privacy warning

* Fix react-router-scroll

* Add image descriptions to `title` attribute to view on mouse hover/long-press.

* Too many title properties may spoil the broth.

* unite loop process
* add hint for original emojifier

* Do not debounce emoji search

* Make autosuggestions appear sooner

* Upgrade to React 16.0.0

* Disable some uncritical tests while chai-enzyme remains incompatible

* Remove react-sizeme

* Fix aspect ratio in "sensitive" mode

Translate "about" page, several settings pages, data export/import,
sessions overview, authorized followers page, account deletion page.

More consistent use of words:
- A toot is a Beitrag.
- An account is a Konto.

Some small improvements.

Blaze it

Create activerecord.de.yml (50%)
Update devise.de.yml
Update doorkeeper.de.yml (100%)
Update simple_form.de.yml (100%)

* Improve performance of modal and swipe animations

* Fix eslint issues

* 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

* Remove web UI warnings about OStatus privacy

* yarn run manage:translations

- 500.html generated with admin-set default locale if set
- Error page `<title>` includes Mastodon site title
- 500 title changed to "This page is not
  correct" (ref: <https://www.youtube.com/watch?v=2VCAP_seh1A>)
- 500 content appended with "on our end" to make clear it's
  not user's fault

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.