Text and Data Mining valid from 2016-12-01
Received: 16 August 2016
Accepted: 22 November 2016
First Online: 16 December 2016
Change Date: 15 February 2017
Change Type: Update
Change Details: The PDF version of this Article previously published contained incorrectly sized figures. This has now been corrected in the PDF version of the Article; the HTML version was correct at the time of publication.
: The authors declare no competing financial interests.