mod_http_muc_log: Move language attribute onto body itself One could argue that it's mostly the message that is in a particular language, while the timestamp is less so. What language a particular nickname is, and its relation to the language in the text, that is an unresolved question.

This module writes out a traceback to `traceback.txt` in Prosodys data
directory (see `prosodyctl about`) when the signal `SIGUSR1` is
received. This is useful when debugging seemingly frozen instances in
case it is stuck in Lua code.