0025231: DRAW - make top level menu useful

-Meaningful texts are provided instead of commands in File menu (e.g. restore->Load Shape (restore))
-tk_getOpenFile is used in "open file" dialogs
-tk_chooseDirectory is used in "change directory" dialog
-Added menu "Help" with submenus "System info", "Commands", "About", "User Guide"
-Added menu "Samples" with submenu "View samples"
-Added menu "Load" with submenus "pload <Module>"

samples/tcl/VisualizationDemo.tcl

@@ -1,5 +1,8 @@
 # Copyright (c) 1999-2014 OPEN CASCADE SAS
 #
+#Category: Demos
+#Title: Displaying 3d viewer
+#
 # This file is part of Open CASCADE Technology software library.
 #
 # This library is free software; you can redistribute it and / or modify it