Function IsNumber

opt_utils/src/json.cpp:85–88

		return (c == '\n' || c == ' ' || c == '\t' || c == '\r' || c == '\f');
	}
	inline bool IsNumber(char c)
	{
		return ((c >= '0' && c <= '9') || c == '.' || c == '-');
	}

	Node::Node()
	{