[airstrike] Recent changes.

[Ulf Ekström]

> Could you update the default level settings file too?
> Now I'm getting a segfault from that. :-)

Yes! Of course! I don't have it at hand right now, but you can try:

title "level 0"
gravity 0.05
bounce 0.5
sprite draco 400 400
sprite biplane 400 100 p1plane
ai player1 p1plane

in share/levels/0/settings.

It's a bit strange that it segfaults with the old file thought, I will
look at that.

Ulf