Gtk2::Dialog enhancements

["muppet" <scott asofyet org>]

discovered that no functionality equivalent to gtk_dialog_new_with_buttons was
implemented, so i did.  is there

instead of having another constructor, you specify the new_with_buttons args
to new, in the same vein as the multi-purpose new for Gtk2::Button.

i also made some changes to the way the response ids are handled.  the dialog
functions were accepting only ints, but run() was attempting to return a
GtkResponseType enum, resulting in rather annoying problems...  i changed this
so that the functions accept either response type enums strings or integers,
and run() returns a string if the return code maps into the enum, and
otherwise an integer.   this allows you to specify stock response codes as
well as custom ones.

i didn't remove any behaviour, by the way, this is only enhancements (making
it work correctly, IMHO).

the old way:

  $d = Gtk2::Dialog->new;
  $d->add_button ("gtk-ok", -5); # -5 => GTK_RESPONSE_OK
  $d->add_button ("gtk-cancel", 42);
    # if the user clicks this button, the program will croak
    # when it fails to convert 42 to a GtkReponseType string

the new way(s):

  $d = Gtk2::Dialog->new;
  $d->add_button ("gtk-ok", 'ok');
  $d->add_button ("gtk-cancel", 'cancel');

  $d2 = Gtk2::Dialog->new ($title, $parent, ['destroy-with-parent'],
                           'gtk-ok', 'ok',
                           'gtk-cancel', 'cancel',
                           'the answer', 42);

(note that 'gtk-ok' and 'gtk-cancel' are the stock ids for stock OK and Cancel
buttons.)

-- 
muppet <scott asofyet org>