mod_firewall: Load a script completely or not at all Previously it was possible that some chains would load, but others would not. This can be surprising (that a "half-loaded" state is possible) and hard to debug. This change makes it so that if some chains don't compile, the whole script will be treated as not loaded.

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.