Funding for this research was provided by:
Xunta de Galicia (EM2014/032)
Ministerio de Educación, Cultura y Deporte (FPU scholarship)
AIE Spain and FEDER (MTM2013-43014-P and MTM2016-75140-P)
Received: 21 October 2018
Accepted: 7 February 2019
First Online: 15 February 2019
: The authors declare that there is no conflict of interest regarding the publication of this article.