Hello Guix!

I found out about a really neat little pixel art editing tool called
Aseprite, so I packaged it!

Allegro 4 is licensed under a weird license called the "giftware"
license that is *very* similar to the Expat license.  But fear not, it
is a free license and Allegro 4 is included in Debian and fully free
distros like Trisquel.  I named the Allegro 4 variable "allegro-4"
instead of just "allegro" because Allegro 5 is the latest and greatest
version of Allegro but I just haven't packaged it yet.

TIA for review!

P.S. - Have a happy FOSDEM!

- Dave