[airstrike] Joystick support (small fix)

[Ulf Ekström]

Hi,

> The files src/core/joystick.[ch] are missing in CVS and I changed a few
> things in the joystick code. A patch against the current CVS version is
> attached to the mail.

Oh, damn. I will apply your latest patch then and remember to add the files.

> The patch adds 3 files (doc/joystick.txt and src/core/jostick.[ch]) in
> addition to modifying src/engine/ai.c.

Thanks again. 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).

Ulf