Improved lighting

I did a bunch of stuff since last post. The easiest to see parts are the lighting changes, but I also:

• Fixed a gamepad-detection issue.
• Improved the ergonomics of the collision module.
• Wrote code to keep paddles on the table.
• Added believable momentum trading for colliding pucks.
• Added keyboard controls.
• Added object-removal support.
• Fixed some debug settings.
• Fixed a bug where glancing circles would get stuck.
• Added the ability to scale meshes in the renderer.
• Added decal rendering.
• Made audio buffer accessible to the simulation thread.
• Increased light smoothness and fixed some light attenuation bugs.
• Added HSV color functions for sha
  ders.
• Added plexiglass panels and tinted the ice.

 Oh. And here's what the table looks like when everything is smooth metal: