Add LightComponent

[jamesaorson]

Adding a LightComponent also requires adding flags to Drawable2DComponent and Drawable3DComponent describing whether or not to render with lighting.

Render2DSystem and Render3DSystem will also need to be aware of how to render with LightComponent.

LightComponent should also have a LightSystem, but similar to CameraComponent, LightComponents are active for a specific set of Render2DSystem and Render3DSystem.

http://rbwhitaker.wikidot.com/basic-effect-lighting