* glib/Object.cs : Added public Handle property. It would be nice
if I could make the RawObject public for get and protected for set,
but that doesn't appear to be possible with C# properties.
* gtk/Container.cs : New class with 2 of the 3 props and the Add/Remove
methods only implemented.
* gtk/Widget.cs : Added SizeRequest prop which is a combination of
HeightRequest and SizeRequest. Embrace and extend gtk...
* gtk/Window.cs : Derive from newly added Container subclass.
* sample/ButtonApp.cs : Simple tire-kicking app.
svn path=/trunk/gtk-sharp/; revision=1112
