InteropGen - assert to make sure accessor's a not null
Remove SceneCamera.IsMainCamera
Add Scene.Camera (returns best, mainest camera)
Add Scene.Camera unit test
Added CameraComponent.PointToScreenNormal, PointToScreenPixels, ScreenPixelToRay, ScreenNormalToRay
Make stuff use Scene.Camera instead of Camera.Main
Remove some Camera members
Remove some functions from Screen