Acknowledgements

"The lighthouse" image, used for the credibility page, is by F.H. Mira and released under a Creative Commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0) License.

The image IMG_2900 used for the visibility page is by Walter Rodriguez and released under a Creative Commons  Attribution 2.0 Generic (CC BY 2.0) License.

The "Ice cream grip" image, used for the award page, is by Daryl Sim and released under a Creative Commons  Attribution-NonCommercial-NoDerivs 2.0 Generic (CC BY-NC-ND 2.0) License.

We thank the authors for their interesting artworks and for sharing them on the web.