99 bottles of beer

[<bma...@we...>]

I just noticed that gnuplot does not have it's own version of the
famous 99 bottles of beer song (http://99-bottles-of-beer.net/).

Here I present my version for discussion before I submit it.
On the site it is stated that "Your example should demonstrate the
main advantages and features of the language". I would appreciate
suggestions to improve the script with respect to this.

Bastian