derive GtkObject from GUnowned, so it initially has a floating reference

derive GtkObject from GUnowned, so it initially has a floating reference

Thu Dec 22 16:01:27 2005  Tim Janik  <timj@imendio.com>

        * gtk/gtkobject.c: derive GtkObject from GUnowned,
        so it initially has a floating reference count.
        gtk_object_class_init(): installa floating flag handler with
        libgobject, so for GtkObjects the flag is stored as GTK_FLOATING
        in the ->flags member.

        * tests/floatingtest.c: test floating flag uses.