Answers to the Comments of Reviewer #1 and Related Actions on the Paper

FOREWORD The authors are obliged to the reviewers for the time spent in revising the paper. In the following pages, we describe in detail how their concerns have been addressed. Some of the requests of the reviewers imply adding a lot of material in the paper. For space limitations we added this material to the extended version of our paper, which is available on line [17] and we referenced such additions in footnotes in the main paper. We can add this material in the main paper if the Editor agrees or if the reviewers suggest what we can remove from the current paper to make room for the new text.