[airstrike] Joystick support (small fix)

[Erik Auerswald]

Hi,

> As you might have noticed I added reading of the
> joystick definition from a configuration file:
> 
> ai->joy_accelerate = conf_number(key_conf,"joy_accelerate",JOY_AXIS1_NEG);
> 
> This means, give me the value of joy_accelerate in the config file if
> it exists, else set it to JOY_AXIS1_NEG and return that value. I will
> also add some method to change the values inside the game, and save
> them.
> 
> If you want to see the current state of the configuration "database"
> you can hit F1 in the game and write "resource" (in the terminal you
> started the game from).

I've noticed it (the changed code) and I'll take a look at this.
So doc/joysticks.txt has to be rewritten...

Erik