Both reviewers made very valuable comments and raised several questions, which should be addressed in a revised version of the manuscript. From the authors reply letter, I can see that the authors are aware, how and where the manuscript can be improved, and what information needs to be included in the revised version. Therefore, I invite the authors to submit a revised version of the manuscript. Based on the comments and questions of reviewer #2, major revisions are required. However, I feel competent enough to make an editor review on the revised version only, if all questions and comments are satisfyingly addressed and the manuscript is improved, such as it is indicated in the reply letter.

The authors addressed all major and minor referee comments in the reply letter and in the revised version. Important information was added to the text and is now also given in the supplementary information. Minor comments and corrections were also satisfyingly implemented in the revised version. I am therefore pleased to accept the manuscript after some technical corrections. Bernd Wagner