0027235: Export GDT: Annotation plane and Presentation.

Implement Null_Style STEP type.
Implement export of annotation planes and presentation as tessellated geometry.
Add tests.

src/StepVisual/StepVisual_NullStyle.hxx

@@ -0,0 +1,25 @@
+// Created on: 2016-03-09
+// Created by: Irina KRYLOVA
+// Copyright (c) 2016 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in OCCT
+// distribution for complete text of the license and disclaimer of any warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#ifndef _StepVisual_NullStyle_HeaderFile
+#define _StepVisual_NullStyle_HeaderFile
+
+#include <Standard_PrimitiveTypes.hxx>
+
+enum StepVisual_NullStyle {
+  StepVisual_Null
+};
+
+#endif