Adopt policy regarding non-standard emoji

[KAMiKAZOW]

In https://github.com/Ranks/emojione/issues/417 I proposed that EmojiOne adopted Windows10’s "Hacker Cat" ZWJ sequence but others disagreed because it's not standardized.

I think we should come up with a rough policy or guideline regarding such emoji, considering we accept contributions.

Basically there are three approaches:

• Adopt only formally standardized emoji and Unicode characters.

• Adopt emoji that are not standardized but used by reasonable large industry players.

• Adopt an "anything goes" policy and allow to come up with our own ZWJ sequences.

My personal preference is the second one. If a reasonable large player in the industry (maybe in the ballpark of 50 million users) introduces a ZWJ sequence, we should be open to accept it.

[Crissov]

I tried to phrase the README in a welcoming open-source spirit that encourages people to add more artwork. I'm thus leaning more towards your third option.

I believe these should be welcome:

• Compatibility graphics for existing characters or (ZWJ) sequences thereof that are treated as emojis by at least one other vendor, see L2/16-087/088 and this spreadsheet. I actually believe it should be a goal of this project to cover all of them, but not the primary objective.
• Extended graphics for other codepoints of pictograms that for no obvious reason do not have the Emoji attribute in emoji-data.txt, esp. from U+26xy, U+27xy, U+2Bxy, U+1F3xy-1F5xy, U+1F6xy, U+1F9xy or perhaps a combination of attributes like this. This includes Rifle and Modern Pentathlon, obviously.
• Established ZWJ sequence patterns applied to other bases, e.g. gendered animals with U+2640/2, or other determiners, e.g. more symbolic flags with Waving White/Black Flag as a base – Rainbow Flag is documented, Twitter's Jolly Rogers is not – or more professions with :man: and :woman: as a base.
• Alternate graphics, e.g. portrait and full body view of any animal (where vendors disagree already) or an alternative that resembles the style chosen by a different vendor than Apple, incl. original Japanese telcos, or localized variants (for instance of :stop_sign:). These could be made available in Opentype fonts via the salt, calt, locl and similar features.
• Flags for RIS sequences that map to private-use codes in ISO 3166-1, e.g. XS, or to deprecated codes in CLDR, e.g. SU.
• Custom ZWJ sequences that follow real-world usage, e.g. a replacement for the frequently seen sequence :point_right::ok_hand: (without ZWJ).
• Emoticon ZWJ sequences of an facial base (incl. animals, sun and moon) and at least one accessory (e.g. :dark_sunglasses:) or mood symbol originally intended for that purpose (e.g. :anger:, :dizzy:, :sweat_drops: or :bulb:).
• Animated variants, especially for those emojis that were animated in one or more of the J-Carrier sets or in popular instant messengers.

These should be discouraged:

• "Memes", e.g. Trollface, and other fads unless transferred to emoji style and using an obvious Unicode sequence.
• Company logos or mascots. (Exception: I would be okay with a glyph variant of :apple: or :green_apple: with a byte taken out, a Tux-looking :penguin:, a more Android-like :robot: etc.)
• Graphics only available from PUA codepoints. (Exception: compatibility graphics for original Japanese emojis.)

Anyhow, the primary focus should be on supporting new emoji codepoints introduced in Unicode 10.0 and later. To get there, we need designers. I'm only able to do simple mashups, but am willing and able to do some coding and administrating.