Renamed setup gtk2 files to gtk ones to support gtk3 only.
Ported to GTK+ 3.10 to fix the deprecated APIs.

GtkTable        -> GtkGrid
GtkVBox         -> GtkBox
GtkHButtonBox   -> GtkButtonBox
Changed the static GtkBuilder file to the resource file.
Changed set_logo_name to set_logo in GtkAboutDialog.
Deprecated GtkStock