* Add assets from Twemoji 13.1.0

* Update emoji-mart

Fixes #14768

* Add emojis:generate_borders Rake task

* Address review

* Border all dark emoji

* Combine stroke with filter to reduce artifacting

* Cleanup Camera with Flash

* Add stroke-linejoin="round"

The previous filter and tweaks were effectively a poor imitation of it.
There are no artifacts for any dark emoji now!

* Set stroke-width using property

This fixes old versions of Firefox.

* Store emoji in string instead of array

* Use separate arguments for each path segment

* Remove "background: black;"

* Update Twemoji to 12.1.5

SVGs from Twemoji repo https://github.com/twitter/twemoji

* Update emoji_map.json to Unicode 12

* Update to emojimart 2.6.1
WIP using local updated version. Sheet comes from emoji-data@4.0.4,
file sheet_twitter_32_indexed_256.png.

* Update to 2.6.1 and uncompress data if needed

* Remove changes that were not needed

* Fix yarn lock file

* Match emojiToShowFilter behavior to new version of emoji-mart

* Fix codeclimate issue

* Match custom emoji behavior to new version of emoji-mart

* Replace emoji without shortcode in tests

* Fix code climate issues

* Switch from EmojiOne to Twemoji, different emoji picker

* Make emoji-mart use a local spritesheet

* Fix emojify test

* yarn manage:translations