-------------------
- ``.attr('value', '')`` no longer removes the ``value`` attribute
- ``<input type="checkbox">`` without ``value="..."`` have a ``.val()`` of
``'on'``
- ``<input type="radio">`` without ``value="..."`` have a ``.val()`` of
``'on'``
- ``<select>`` without ``<option selected>`` have the value of their first
``<option>`` (or ``None`` if there are no options)