Deprecate.

Deprecate.

        * gdk/gdkdrawable.h (gdk_drawable_ref, gdk_drawable_unref),
        gdk/gdkcolor.h (gdk_colormap_ref, gdk_colormap_unref),
        gdk/gdkdnd.h (gdk_drag_context_ref, gdk_drag_context_unref),
        gdk/gdkgc.h (gdk_gc_ref, gdk_gc_unref):  Deprecate.

        * gdk/gdkvisual.h: Use GDK_DISABLE_DEPRECATED, not
        GTK_DISABLE_DEPRECATED.

        * gdk/gdkcolor.c (gdk_colormap_ref, gdk_colormap_unref),
        gdk/gdkgc.c (gdk_gc_ref, gdk_gc_unref): Document.

        * gdk/tmpl/colors.sgml, gdk/tmpl/pixmaps.sgml, gdk/tmpl/dnd.sgml,
        gdk/tmpl/gcs.sgml: Document ref and unref functions as deprecated.