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* Updated documentation
* Added better defaults for schema types
* Updated JQuery in testish
* RadioChoice no longer emits a none_option by default
* Overhauled the missing/empty strategies
In order to allow a user to represent both an empty string and a None value
at the same time, a few updates had to be made to how the widgets worked.
Hopefully most of these will be backward comptaible but we can't assure this
without a lot of checking. We now have a none_value attribute which
represents the value that is shown to a user to represent None. We also have
the old empty attribute which is used if the widget produces data which
matches the none_value. Have a look in testish for InputNoneValue for an
example and also InputDateNoneValue. Another example is
SelectChoiceWithEmptyString which shows how to allow both '' and None to be
selected.