Hello,

The following patch adds Scratch to the Guix packages.

There are some caveats:

- it is not the latest version of scratch (1.4 instead of 2.0) as this
  one required Adobe Air for the offline editor and Flash plugin online.

- it freezes when returning from fullscreen execution of a script. Note
  that the same happens with the Debian package, so there's probably
  little I can do.

- the installation merely copies Scratch.image, which is an image of the
  VM. It is not a binary blob. You can inspect and modify code from
  within the application. See
  <https://wiki.scratch.mit.edu/wiki/Scratch_1.4_Source_Code> for details.

- "/usr/share/scratch" directory is hard-coded. As a consequence Scratch
  cannot find translation files or artwork. You can still import artwork
  from the store directory but it is not a great out-of-the box
  experience.

  I notified the issue to the developers
  (https://github.com/LLK/Scratch_1.4/issues) but, considering other
  issues there are years old, I have little hope about it.

  If there's an idea on how to fake the "/usr/share/scratch" directory,
  I'm all ears.

Feedback welcome.

Regards,

-- 
Nicolas Goaziou                                                0x80A93738