* configure.in.in: add new dir and autofu for it.
* Makefile.am: add new dir
* gapi/*: a small extension method library to add generation-related
api to GType in 2.0. Access it with -pkg:gapi-2.0-compat to pick up
the needed refs.
* generator/GObjectVM.cs: generate new GType getter methods.
* generator/ObjectGen.cs: generate new GType getter methods.
* glib/GType.cs: change a few props to methods to make them extension
method friendly for 2.0 compat.
* glib/Object.cs: use new GType getter methods.
* glib/Value.cs: use new GType getter methods.
* gtk/Widget.custom: use new GetClassPtr method.
svn path=/trunk/gtk-sharp/; revision=139609
