mod_audit_auth: Ignore FAST authentication events by default FAST is more like a cookie that allows linking new connections to a previous (e.g. password) authentication. Since we assume that FAST tokens are secure (not user generated) and not shareable, it reduces a lot of noise by filtering out uninteresting authentication events.

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.