TwemojiMozilla.ttf is Twemoji Mozilla 0.7.0, unmodified, from
https://github.com/mozilla/twemoji-colr/releases/tag/v0.7.0

The emoji art comes from Twemoji (https://github.com/twitter/twemoji),
Copyright 2019 Twitter, Inc and other contributors, licensed under the
Creative Commons Attribution 4.0 International licence (CC BY 4.0):
https://creativecommons.org/licenses/by/4.0/legalcode

The font was built by the twemoji-colr project, Copyright 2016-2018 Mozilla
Foundation, whose build code is licensed under the Apache License,
Version 2.0: http://www.apache.org/licenses/LICENSE-2.0
