Make GLib.Object.{Set,Get}Property public
Make GLib.Object.{Set,Get}Property public

The two methods are useful when we don't bind a property or the user
needs to set a custom property.

openmedicus/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp,openmedicus/gtk-sharp