prevent accidental lower casing material names in ReplaceDefaultMaterial

code/3DS/3DSConverter.cpp

@@ -72,7 +72,7 @@ void Discreet3DSImporter::ReplaceDefaultMaterial()
     unsigned int idx( NotSet );
     for (unsigned int i = 0; i < mScene->mMaterials.size();++i)
     {
-        std::string &s = mScene->mMaterials[i].mName;
+        std::string s = mScene->mMaterials[i].mName;
         for ( std::string::iterator it = s.begin(); it != s.end(); ++it ) {
             *it = static_cast< char >( ::tolower( *it ) );
         }