Move fn.dart into /sky/framework

sky/examples/fn/widgets/item.dart

 library item;
 
+import '../../../framework/fn.dart';
 import 'dart:sky' as sky;
-import 'fn.dart';
 import 'widgets.dart';
 
 enum Color { RED, GREEN }
 
 class Item extends Component {
 
   String label;
 
   Color _color = Color.GREEN;
 
@@ skipping 17 matching lines @@
       ]
     );
   }
 
   void changed(Object value) {
     setState(() {
       _color = value;
     });
   }
 }