This makes use of a Markdown extension for rendering Emojis in text
fields. Users can provide shortcodes (like `:smile:`), which will be
turned into image references based on the EmojiOne index (a
comprehensive, free Emoji library).

Emojis can be used in any Markdown-capable text field. Currently,
there's no support for Emojis in the summary field (which will require
some additional changes) and there's no UI to help select Emojis. These
will require separate pieces of work.

Tested various Emojis in text fields. Saw that they rendered correctly

in Markdown mode, with the right sizing. Also saw that they rendered

in the change descriptions' diff view for the text fields.