Formulator TODO

  - When using a BasicForm a field cannot get to the form's 
    get_form_encoding method (where the ZMIForm uses acquisistion 
    to achieve this).
  
  - Make composite fields work well as hidden fields.

  - Add combobox field

  - Add various button fields

  - Investigate duration and time only field.

  - internationalisation (or error messages first)

  - HTML filtering field?

  - Add more unit tests.