0024599: Tools for interacting with DRAW from Visual Studio debugger

Global functions are added to allow a user performing DRAW commands from VS Command Window when DRAW is interrupted on a breakpoint.
Previously existing functions are adapted to work with Visual Studio debugger (Command Window).
A manual describing use of these functions and other debugging facilities and some hints is added to Developer Guides.
Minor corrections and refinement of debug.md.

src/Draw/Draw_Debug.cxx

@@ -0,0 +1,42 @@
+// Created on: 2010-06-02
+// Created by: Peter KURNEV
+// Copyright (c) 2010-2014 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.
+
+#include <DBRep.hxx>
+
+#include <Standard_ErrorHandler.hxx>
+#include <Standard_Failure.hxx>
+
+extern Draw_Interpretor theCommands;
+
+// This file defines global functions not declared in any public header,
+// intended for use from debugger prompt (Command Window in Visual Studio)
+
+//! Execute given DRAW command
+Standard_EXPORT const char* Draw_Eval (const char *theCommandStr)
+{
+  if (theCommandStr == 0)
+  {
+    return "Error: null command string";
+  }
+  try {
+    OCC_CATCH_SIGNALS
+    theCommands.Eval (theCommandStr);
+    return theCommands.Result();
+  }
+  catch (Standard_Failure)
+  {
+    return Standard_Failure::Caught()->GetMessageString();
+  }
+}

src/Draw/FILES

@@ -27,3 +27,4 @@ Draw_Main.cxx
 Draw_PluginMacro.hxx
 Draw_PloadCommands.cxx
 Draw_Window_1.mm
+Draw_Debug.cxx