substitute (c) and (C) for copyright strings as documented

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57245 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/aboutdlg.h

@@ -128,6 +128,10 @@ public:
     // artists and translators) as a one long multiline string
     wxString GetDescriptionAndCredits() const;
 
+    // returns the copyright with the (C) string substituted by the Unicode
+    // character U+00A9
+    wxString GetCopyrightToDisplay() const;
+
 private:
     wxString m_name,
              m_version,