Fix for TextCtrl problem as reported by Vegh

Move definition of wxMenuItem to /gtk/menuitem.h
  Radical change of how to insert a child into a
    paren window. As C++ doesn't have any VMT in
    a class's consructor, I have to use a callback.
  Fixed culumn resizing bug in wxListCtrl
  Fixed menu height bug in MDI code


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@955 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk1/menu.cpp

@@ -7,9 +7,9 @@
 // Licence:     wxWindows licence
 /////////////////////////////////////////////////////////////////////////////
 
-
 #ifdef __GNUG__
 #pragma implementation "menu.h"
+#pragma implementation "menuitem.h"
 #endif
 
 #include "wx/menu.h"