#571 Support extended window styles for dialog and dialog control windows

[Mark Miesfeld]

Some time ago the internal support in ooDialog for dynamically creating a dialog template was enhanced to use the extended DLGTEMPLATEEX and DLGITEMTEMPLATEEX structures.

But there is still no way for the user to pass in any of the extended window style values. Instead, in a few places where and extended style is absolutely needed that style is hard coded internally.

It would be nice if the user could specify these styles when using a UserDialog subclass. In addition, these values end up getting dropped when using a RcDialog subclass.