Issue #1234 - Replace CString in the traverser

src/plugin/PluginUtil.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 12 matching lines @@
 std::wstring UserSettingsFileUrl();
 std::wstring FirstRunPageFileUrl();
 std::wstring FileUrl(const std::wstring& url);
 std::wstring GetLocationUrl(IWebBrowser2& browser);
 
 template<class CharT, class Traits, class Alloc, size_t N>
 bool BeginsWith(const std::basic_string<CharT, Traits, Alloc>& s, const CharT(&beginning)[N])
 {
   return 0 == s.compare(0, N - 1, beginning);
 }
+
+/**
+ * Return a lower-case version of the argument string.
+ * Current version uses 'CString::MakeLower()' to preserve legacy behavior during refactoring.
+ */
+std::wstring ToLowerString(const std::wstring& s);