Issue #276 - introduce class BSTR_Argument

src/plugin/ATL_Deprecate.h

 /**
  * \file ATL_Deprecate.h Include package for all the ATL headers, with optional forwarding to detect ATL dependencies.
  *
  * This header is a nexus for refactoring work to remove ATL.
  * The main purpose of this mechanism is to determine the exact scope of the refactoring effort.
  * The lifetime of this header is during the work on #276 Stop using ATL https://issues.adblockplus.org/ticket/276
  *
  * This file implements namespace forwarding that allows detection of ATL symbols.
  * This forwarding is ordinarily disabled, and always disabled in Release configuration for safety.
  * When forwarding is disabled, it simply includes the ATL headers.
@@ skipping 110 matching lines @@
 #endif
 
 /*
  * Deprecation pragmas use the compiler to identify refactoring targets.
  */
 #if DISABLE_ATL_FORWARDING
 namespace ATL {
 #else 
 namespace OLD_ATL {
 #endif
-//#pragma deprecated( CComBSTR )
+#pragma deprecated( CComBSTR )
 #pragma deprecated( CRect )
 #pragma deprecated( CSimpleArray )
 }
 
 /*
  * Note:
  *   The preprocessor symbols ATLASSERT and ATLTRACE appear in the source.
  *   These resolve to nothing in Release configurations.
  *   In Debug configurations, these are non-trivial.
  *   ATLASSERT resolves to an expression with _CrtDbgReportW and _CrtDbgBreak.
@@ skipping 15 matching lines @@
  *
  * Reference:
  *   MSDN CString http://msdn.microsoft.com/en-us/library/aa300688%28v=vs.60%29.aspx
  */
 
 #include <string>
 /**
  * Conversion function from ATL:CString to std::wstring
  *
  * The argument cannot be declared 'const' because of the CString API.
+ * Reference argument usually does not require explicit temporaries.
  */
-std::wstring to_wstring(ATL::CString& s);
+std::wstring to_wstring(const ATL::CString& s);
 
 /**
  * Conversion function from std::wstring to ATL::CString
  */
 ATL::CString to_CString(const std::wstring& s);