[Simh] Historical gaming devices

[Lars Brinkhoff]

Hello,

I'm adding simulations of some historical gaming devices to SIMH:

- PDP-6/10 Spacewar consoles.  Five switches, times four players.
- PDP-6/10 A/D converter.  Not really gaming, but used for games.
- PDP-11 Dazzle Dart boxes.  Eight switches, times four players.
- PDP-11 Galaxy Game?  I haven't looked at this yet.

The SDL2 library used by sim_video provides inputs from USB joysticks
and game controllers.

If anyone knows about any other similar devices, I'd like to take those
into consideration.