One of my colleagues was so nice to purchase some paper and two bottles of Neutol ECO for me in December 2015 from Fotoimpex while she was in Berlin. I didn't get around using it as I wanted to try out the MCC developer first. By now the (unopened) Neutol ECO has turned bright red. Is this still usable? Yes, I could just try it out but I'd hate to waste time and paper on dead developer. Darkroom time is precious these days. In general, what is the shelf life of Neutol ECO?