Changes since 7.x-1.8:
- Follow-up #1966852: Fixed CSS not adjusted to account for fieldset changed to container element.
- #1980824: Support user and form-provided attributes being output in the wrapping container.
- #1966852: Changed options manual entry to be wrapped with a container element instead of fieldset for less jarring output.
- #1960630: Added support for title and description properties by adding the form_element #theme_wrapper by default.
- #1935544: Changed package name to 'User interface.'