mod_muc_moderation: Copy XEP-0421 occupant-id from retracted message Lets clients correlate the sender of whatever was retracted by moderators. Behavior limited to Prosody 0.12, otherwise there are no assurances of the origin of the occupant-id tag. Ref #1816

<tr>
  <th>What is {x} {op} {y}?</th><td>
    <input name="captcha_challenge" type="hidden" value="{challenge}">
    <input name="captcha_reply" pattern="[0-9]+" required type="number">
  </td></tr>