* gdk/Gdk.metadata : hide some manually implemented callback methods.
* gdk/*.custom : implement several methods containing persistent
callback parameters.
* generator/BoxedGen.cs : set gen_info.CurrentType in Generate.
* generator/ClassGen.cs : set gen_info.CurrentType in Generate.
* generator/Ctor.cs : set gen_info.CurrentMember in Generate.
* generator/GenerationInfo.cs : add CurrentMember and CurrentType.
* generator/Method.cs : set gen_info.CurrentMember in Generate.
* generator/MethodBody.cs : always generate null guarding for array
parameters, and add a nag for callback parameters without a scope attr.
* generator/ObjectGen.cs : set gen_info.CurrentType in Generate.
* generator/OpaqueGen.cs : set gen_info.CurrentType in Generate.
* generator/Parameters.cs : kill NullOk. add Scope property.
* generator/StructGen.cs : set gen_info.CurrentType in Generate.
* gtk/Gtk.metadata : kill a few null_ok attrs.
* pango/Pango.metadata : mark the callback params as call scope. kill
a couple null_ok attrs.
svn path=/trunk/gtk-sharp/; revision=42529
