[airstrike] Airstrike music, direction

[Eero Tamminen]

Hi,

> I've also got a question about the bonuses. Do they actually do anything?
> I have yet to notice any effects from collecting the bonuses.

I did the bonus machine and currently working bonuses, so I'm probably the
best to answer that... What they are intended to do is documented in
'doc/bonus.txt'.

Currently working ones are kind of "enviromental effects. Basically they
make some other game object follow the plane until other of them dies or
player catches the bonus again.  Cloud bonus makes a cloud to appear.
In two player play that could be used to e.g. hide...  Most visible effect
is the "heart" ;-).

Once the level code is ready, Ulf might add rest of the bonuses (bomb,
energy, parachute).

	- Eero