introducing concept of composite widgets for handling YearMonthPicker and MonthDayPicker.
streamlining call point for commiting value changes.
more work on implementing xf:switch.
removing deprecation warning from DatePickerGenerator.
git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@4889 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261