* gtk/gtkspinbutton.h gtk/gtkspinbutton.c gtk/testgtk.c:
        - Bug fix for precision problem causing occasional double emission
	  of "value_changed" signal (hopefully works now).
        - API change (should be binary compatible) :
	  new enum GtkSpinType; modified gtk_spin_button_spin to use it.
	  Modified cursor example appropriately.
	  To spin by something other than step_/page_increment, use
	  gtk_spin_button_spin (spin, GTK_SPIN_USER_DEFINED, increment).
	- Made GTK_SHADOW_NONE the default. ;)
	- Fixed casting of GtkAdjustment* to GtkWidget* in
	  gtk_spin_button_value_changed.