bug#11016: 24.0.94; Right-to-left GUI

[martin rudalics]

> Some prefer one, others prefer the other.  It should be a separate
> user option, because there's no one-fits-all solution, and basing the
> solution on the locale is definitely wrong (one can work in a R2L
> locale without speaking any R2L language).

We probably should use gtk_menu_bar_set_child_pack_direction right
after the gtk_menu_bar_new call in create_menus according to that user
option.  Its values would probably be 'left-to-right', 'right-to-left'
and nil - to leave the decision to the locale.

martin