Add timeout loop so long-held keys don't decay on the server and add
processing of simultaneous acceleration/rotation controlState messages
coming in from the FE.
Add sprite rotation to the tank display.  Hey, I have real movement now!
Changed control state system to update all controls in a single command.  Call Tank.fire() if trigger goes from off to on
Bullets add and move
Bullets now decay, but the bullet list leaves nil entries
Bullets fade away properly now
Firing bullets!  Dumb javascript model though.
Removed debugging output
proper tracking of bullet sprites