Add new dialog4ports
This will be used soon to replace the old dialog(1) for make config
It implements a new mixeddlg widget which allow to mix radio and
classic buttons in a single interface allowing the UI to reflect
Bundle libdialog on 8.x which doesn't provide a recent libdialog(3).
Thank you very much to Ilya A. Arkhipov who wrote it,
helped by danfe, eadler and myself