This collaborative work is licensed under the  CC0 1.0 Universal (CC0 1.0) 
http://creativecommons.org/publicdomain/zero/1.0/

It means that the authors:
  - Fabien Cissé
  - Karine Paris
  - Marie Moriamé
  - Martin Potier
  - Vincent Maugis
  - Viviana Sarac

have dedicated the work to the public domain.