Function convertInto

tests/catch.hpp:6959–6967

    template<typename T>
    inline auto convertInto( std::string const &source, T& target ) -> ParserResult {
        std::stringstream ss;
        ss << source;
        ss >> target;
        if( ss.fail() )
            return ParserResult::runtimeError( "Unable to convert '" + source + "' to destination type" );
        else
            return ParserResult::ok( ParseResultType::Matched );
    }
    inline auto convertInto( std::string const &source, std::string& target ) -> ParserResult {
        target = source;
        return ParserResult::ok( ParseResultType::Matched );