[cla][patch][test] Changing constraints on DateTimeBox more than once doesn't always work

[nathan]

(kind of related to bug #5610)

The calendar caches it's "disabled" set of dates - so changing constraints after the popup has already been displayed once will not result in a new set of constraints. The constraints are honored - but the visible set of "disabled" dates is not updated.

Attached is a patch to dijit.form._DateTimeTestBox to force a redraw of the calendar if the popup has already been displayed and the constraints have been changed. A test case is also applied to test_DateTextBox that adds a "To/From?" pair of date boxes.

[guest]

Patch by Nathan Toone to allow for dynamic changing of constraints

[nathan]

Updated patch to destroy the calendar widget on blur - rather than hacking around it...no noticable performance difference in IE6

[bill]

Looks good to me; keeping around the drop down seems like a premature optimization (that leads to problems like this).

[Douglas Hays]

(In [12736]) Fixes #6002 !strict. Proxy commit for nathan. Destroy popup on blur so that changed constraints are reprocessed. Add to/from datetextbox example.