© 2018, The Author(s). The original version of this article unfortunately contained mistakes. The Tables 1–3 were missing. The correct versions of Tables 1, 2 and 3 are given below. Bettina Standhartinger was unfortunately not correctly named in the acknowledgments of the original version of this article. The correct acknowledgements are as follows: The authors would like to thank Bettina Standhartinger for her valuable assistance in organizing the Wiggers–Bernard Conference.