Linux force feedback wheel support

[jdeneux]

I gave it a go, but it was not too successful. My joystick is listed in the game, but it behaves as if it had no axes (no blue boxes at all when calibrating). That is not specific to VDrift though, I suspect a bug in my version of SDL, or maybe in the driver.
So I played with the keyboard, and kept a hand on the joystick to feel if something was moving. I never managed to achieve high speed (past the 3rd gear) with the default car playing with the keyboard: In curves, the car just understeers, I spent more time in the grass than on the road

I never felt anything, maybe the forces were just too weak. I got many error messages related to failed effect updates. That happens with ffcfstress also, and is due to the iforce device not being happy about receiving too many packets too fast.

The joystick is supported by the iforce module, not the hid module. I will try with a wheel and see if I have more success.

The joystick worked with ffcfstress, although it did not behave fully as expected. The stick would jerk violently if I started moving it instead of just holding it in the centre position.

To summarize: It seems VDrift isn't doing anything wrong, but the experience was not quite successful.