C++11 : Use using instead of typedef

C++11 type alias.

Author: ya1gaurav

src/lib_json/json_reader.cpp

@@ -55,9 +55,9 @@ static size_t const stackLimit_g = JSONCPP_DEPRECATED_STACK_LIMIT; // see readVa
 namespace Json {
 
 #if __cplusplus >= 201103L || (defined(_CPPLIB_VER) && _CPPLIB_VER >= 520)
-typedef std::unique_ptr<CharReader> CharReaderPtr;
+using CharReaderPtr =  std::unique_ptr<CharReader>;
 #else
-typedef std::auto_ptr<CharReader>   CharReaderPtr;
+using CharReaderPtr = std::auto_ptr<CharReader>;
 #endif
 
 // Implementation of class Features