mod_smacks: Send out more ack requests where needed Under some circumstances it was possible that more than "max_unacked_stanzas" where left in the outgoing stanza queue without forcing an ack. This could happen, when more stanzas entered the queue while the last ack request was still unanswered. Now the test "#queue > max_unacked_stanzas" is done upon receiving an ack as well as when sending out stanzas, which fixes this bug.

This module adds a command to `prosodyctl` for listing users.

``` sh
prosodyctl mod_listusers
```