Fix warning for unused variable.
Add two more DEFCTYPES to fix warnings.
Initialize types GdkGLPixmap, GdkGLWindow.
Move registration before first type query.

Fixes warnings, but may not be completely correct.
Patch for the majority of the gtk drag'n'drop API. This changes
selection-data to g-boxed-opaque and _removes_ boxed-copy-fn from
parsed GValues.  Also establish selection-get and selection-set for
easy selection data access.
Fixup for selection-data where format=32.  X specification is odd.
Added basic, ugly convenience function for cairo->pixbuf conversion,
so cursors can be drawn on a cairo image surface.  gtk-drag-dest-set
now passes (null-pointer) if targets is nil; this invokes a special
case in gtk where all dragging can be handled by the client.

Conflicts:

	cairo/cairo.lisp
	gdk/gdk.pixbufs.lisp
 Merge subset of commit '4a6ca9e91e82da3047bd0029296e00e9030a3686' of git://github.com/Valera/cl-gtk2

    So it seams axes of length 7 is correct, i.e. GdkAxisUse has that
    length.  However I don't see why we even need a FIXED-ARRAY there
    when there GDK functions to retrieve the respective axis anyway.