* glib/Object.cs (Ref): Added.
* gtk/Object.custom (Ref): Overload. Note that we were reffed.
(DisposeNative): Unref if we were explicitly reffed.
* generator/Method.cs: Call Ref if needs_ret is set.
* generator/StructBase.cs: Call Ref on all object accessors.
* glue/style.c: Ref returned GCs.
* sources/Gtk.metadata: Set needs_ret on various gdk-related
accessors in GtkWidget. Hide Ref/Unref methods on Widget and
RcStyle as these ought to be deprecated anyway.
svn path=/trunk/gtk-sharp/; revision=7380