Bind additional keys for keyboards without a keypad

Additionally binds this layout to the keyboard player:
q/w/e
a/s/d
z/x/c


I noticed you want to avoid new features and are ok with bugs.  I consider this a bug since, without a keypad, I was unable to play.

BTW, regardless, thank you for putting this together.  I'm just getting started with D and it's a nice jumping off point.  Your game helped me make sure all my dependencies were setup correctly (rather than relying on the surely broken SDL code I would have written).