New feature: Basic support for physically based rendering (PBR)

Thanks for testing. A file was missing from SlicerSandbox that prevented the packaging. I’ve added the file now. If you don’t want to wait for tomorrow’s release, you can download the extension from here and add the Lights folder to the Modules → Additional module paths in your application settings.

I’m not sure what’s going on with the macOS build. @Sam_Horvath can you have a look?