re-add hidden inputs for day/month/year. dont display seperators if one of the fields isnt shown
fix widget_year tests
fix widget_monthyear tests
fix widget_date tests
fix widget_datetime tests. converter changed, how empty timezones are handled. now they are returned as empty strings instead of None. KEEP AN EYE ON IT, IF THAT MAKES SENSE....
remove "required" class, since z3c.form its only rendered in input mode.
changelog note
remove unnecessary output in tests