Region#show return 'this'

Adds the capability to write

    myRegion1.show(new MyLayout1());
    myRegion1.show(new MyLayout2());
    myRegion1.show(new MyLayout3());

as

    myRegion1.show(new MyLayout1())
             .show(new MyLayout2())
             .show(new MyLayout3());

and nested layouts:

    myRegion1.show(new MyLayout1());
    myRegion1.currentView.myRegion2.show(new MyLayout2());
    myRegion1.currentView.myRegion2.currentView.myRegion3.show(new MyLayout3());

as

    myRegion1.show(new MyLayout1())
      .currentView.myRegion2.show(new MyLayout2())
      .currentview.myRegion3.show(new MyLayout3());