[Xfce 4.8] Migrating from libglade to gtkbuilder [Gtk+ >= 2.12]

[Stephan Arts]

Hi Guys,

I know that with 4.6, we chose to use libglade to generate
settings-dialogs. I'd like to propose moving from libglade to
gtkbuilder (already in gtk since 2.12).

If you guys agree, I want to start working on it in xfce4-settings.

Regards,

Stephan