Automatically analyze the parameter type and invoke the 'operator<<' interface to transform it to string.
/**
@fn to_string
@brief transform the input value to string
@param [in] T the value type is transformed to string
@param [in] RefT the value reference to translate
@param [in] split split mark between two element if have
@return formated string
*/
template< class T> std::string to_string( const T& RefT, const char* split=" ")
