Add support for more than 1 joystick.

[pkali]

Ideally it would work with 1 (all versions), 2, 3 or 4 controllers.

problem - how to assign player to a controller? maybe an additional line in the difficulty level selection for human players?

[Use controller]: [ 1 ] [ 2 ] [ 3 ] [ 4 ]

with a default set to [ 1 ]

[Pecusx]

Done!