tl;dr: a lot of small improvements and fixes, a couple of big-ish features
Biggest changes are:
- the data structure that holds the parsed data from GTK now incorporates emoji keywords;
- completion now searches trough the keywords;
- support for localized emoji data (based on application locale).
The language should better be chat-specific, but that would be a not-so-small refactoring, probably. Also, there aren't a lot of languages in the latest GTK 3.x tag currently, master has more, and CLDR -- over 9000.
Smaller things are case-insensitivity and better UX when typing classic text "emoji". :P