[SDL] Adding SpaceNavigator support to libSDL

[Ettore Pasquini]

I have something working for the SpaceNavigator.  Two questions:

1. To get the correct number of axes I had to add it as a special "relative" event device.  This works, but it would be nicer to have SDL inspect the number of axes dynamically.  Is there a way to do that with a relative device?  I'm not a Linux expert.  The code inside EV_ConfigJoystick reports 0 axes (I can't find an analog of EVIOCGABS).

2. Second problem is calibration.  How is this achieved in SDL for regular joysticks?  A few pointers in the code would suffice.

Thanks,

Ettore