Add package for Typespeed game

[auntieNeo]

I packaged the classic Typespeed typing game for Nix. By default, typespeed stores high score files and such in /var and /etc, which is problematic in Nix. I wrote a rather lengthy patch that creates a ~/.typespeed directory with ~/.typespeed/score and ~/.typespeed/config when typespeed is started.

I wasn't sure how I should add myself as a package maintainer, so I left that out for now.

[7c6f434c]

I think if you add a significant patch, it is better to add yourself as a maintainer.

Also, the preferred way of listing licenses is via stdenv.lib.licenses.

[auntieNeo]

Alright, I added myself as a maintainer and set the license as you suggested.

[Fuuzetsu]

It's probably also better to squash your work into few coherent commits after you're done hacking on it: no need for everyone to see files added by mistake &c