Move wxTopLevelWindow::SetShape() down to wxNonOwnedWindow.

Also add wxNonOwnedWindow for wxMSW (which previously simply typedef'd it to
wxWindow) and document this class now that it provides some user-visible
functionality.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@69364 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/osx/toplevel.h

@@ -51,9 +51,6 @@ public:
 
     virtual wxPoint GetClientAreaOrigin() const;
 
-    virtual bool SetShape(const wxRegion& region)
-        { return DoSetShape(region); }
-
     // Attracts the users attention to this window if the application is
     // inactive (should be called when a background event occurs)
     virtual void RequestUserAttention(int flags = wxUSER_ATTENTION_INFO);