mod_traceback: Hook signal via event instead of directly
Safer this way, see Prosody trunk rev 69faf3552d52
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summary: Set process name to prosody
...
This module sets the process name to `prosody` so it shows up as such
instead of `lua` in process management tools.
To use this module, you'll need the proctitle Lua library:
<https://github.com/hoelzro/lua-proctitle>