[mikhail]

Update:
I finally succeeded connecting the two webhooks: from TBA to Slack. Yay! It's a -nasty hack- convoluted Python script running on Google Apps. So far it is very simplistic, basically just stripping JSON formatting for a couple of message types. I can't open-source it yet because all the URLs and secrets are hard coded into the script. I'll see how it works this upcoming weekend then will try to rewrite it in a more open-source-able form (after I'm done with my taxes as well). Stay tuned.