Use NSDatePicker to implement both of these controls. Almost all of
wxDatePickerCtrl styles are not supported in the native version but the basic
functionality does work and looks much better than the generic version (which
is still available as wxDatePickerCtrlGeneric if needed) under Mac.
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@70071 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
