Characters with a Unicode derived age that's older than the Emoji form should require VS16

[jmcwilliams403]

Certain Unicode characters have original intended uses that aren't Emoji. If a character was introduced into Unicode before it was added as an Emoji, forcing the Emoji form should require appending VS16 (U+FE0F) after it in the text stream, but otherwise it should be displayed as plain text.

[samhocevar]

I think this is more or less #18, what do you think?