use when the IntPtr is NULL.
* generator/SignalHandler.cs, generator/CallbackGen.cs: removed
call to Initialize for structs
* gtk/Clipboard.custom, gtk/ClipboardClearFunc.cs,
gtk/ClipboardGetFunc.cs,
gtk/GtkSharp.GtkClipboardClearFuncNative.cs,
gtk/GtkSharp.ClipboardGetFuncNative.cs, SelectionData.custom:
Hand-wrapped selection handling stuff, along with relevant
signals and the like.
* gnome/voidObjectAffineSVPintSignal.cs: removed Initialize
for hand-wrapped signal
* sample/GnomeHelloWorld.cs, sample/Size.cs: compare against
.Zero instead of using IsNull
* api/gtk-api.xml, sources/Gtk.metadata: metadata updates for
hiding some manually-wrapped stuff
svn path=/trunk/gtk-sharp/; revision=8912
