-----
- test coverage
[rnix, 2011-05-07]
- add widget value validation checking 'multivalued' property against 'value'
length.
[rnix, 2011-05-07]
- remove outdated ``_value``. user ``fetch_value`` instead.
[rnix, 2011-05-07]
- add optional ``for`` property for label widget.
[rnix, 2011-04-23]
- select extractor - fix required behavior
[rnix, 2011-04-19]
- compound renderer - consider 'structural' property on widget node
[rnix, 2011-04-19]
- number extractor - return val if UNSET
[rnix, 2011-04-14]
- textarea renderer - check value against None and render empty string instead
[rnix, 2011-04-14]