mod_rest: Workaround lack of number coercion in util.datamapper for HTTP upload util.datamapper will not coerce a string into an integer like the XEP-0363 'size' slot, which becomes a problem when using the HTTP GET method, passing fields as ?query parameters which are always strings.

<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>