ffgo.svg was created by Florent Rougon with Inkscape, from the following
openclipart icon:

  https://openclipart.org/detail/190981/helicopter

which, according to <https://openclipart.org/share>, is in the public domain.
The resulting derived work is also released in the public domain and, if/where
not applicable:

  Copyright (C) 2015  Florent Rougon
  License: DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE version 2, dated
           December 2004
