mod_smacks_noerror: Add ability to silence errors if mod_offline is disabled This will also silence "message not delivered" errors if mod_offline is disabled and all clients are offline. This assumes working MAM for all clients (lready assumed by the rest of this module).

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summary: Log a message once per minute
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This module sends `-- MARK --` to the log once per minute. This may be
useful to give a sense of how busy the server is or see that logging and
timers are still working.