Incorrect xfce_framebox_add() implementation

[Jeff Franks]

Brain,

xfce_framebox_add() is implementated wrongly, especially for language 
bindings. For consistency, xfce_framebox_add() should be a static 
function in xfce_framebox.c that is assigned likewise inside the 
class_init function:

container_class->add = xfce_framebox_add;

As it stands, for language bindings, it creates a naming conflict 
between the Gtk::Container base class and the Xfce::Framebox class. Can 
we deprecate it and add a static function to xfce_framebox.c, something 
like xfce_real_framebox_add(), and add a comment above the deprecation 
that says use gtk_container_add().

I can provide a patch if you want.

Jeff.