Text and Data Mining valid from 2017-02-09
Received: 3 October 2016
Accepted: 10 January 2017
First Online: 9 February 2017
Change Date: 6 March 2017
Change Type: Update
Change Details: The HTML version of this paper was updated shortly after publication, following a technical error that resulted in the incorrect labelling of the Supplementary Videos 1 and 2. This has now been corrected in the HTML; the PDF version of the paper was correct from the time of publication.
: The authors declare no competing financial interests.