[Feature request] Emoji reactions to comments

We're using Trello and, funnily, we rely on this feature (being able to react with emojis to any comment) quite heavily in our team: to show that we've read the comment, that we agree / disagree with the proposal in it, to congratulate / show appreciation, to show we've completed the task set out in it, etc. We'd like to switch to an open-source platform, and this feature would be something we'd miss a lot.