Recently I had the need for a better gitter-irc two-way gateway than gitter-irc-bot. Specifically, I wanted to be able to run multiple mirrors off a single bot/account. I started writing a multi-protocol gateway and the goal was to support slack, gitter, mattermost, irc and possibly matrix with a plugin API.
Here's the prototype: https://github.com/jleclanche/gitterway
It's in python. I started rewriting it in Go and then found out toml support in go was lacking, then I sort of gave up... if anyone's interested in picking it up, file an issue on there!
That author also wrote a test suite in go that compares all the other toml implementations for interoperability. I'd say it's pretty high quality.
I'm kind of un-bullish on toml in general, sadly. I tried toml in a couple of projects, and found for structures nested beyond a certain level, it doesn't really seem all that simple anymore. I ended up going back to json or yaml (only with a parser that doesn't implement most of the fancy features of yaml, for conservation-of-sanity reasons, of course).
Emojis work just fine over IRC, https://i.imgur.com/2EeZYpP.png
Not sure what you mean with "auto expandable URLs", but there probably already exists a script for that.
We need an IRC-based Slack alternative badly!