Add path tracing for PC

I'd like to see real-time path tracing from Nvidia implemented in the PC version. Real-time path tracing is a rendering technique that simulates very realistic lighting in real-time. It is very demanding in terms of computer performance, however. Nvidia has a repository on GitHub that serves as a starting point for integration of real-time path tracing. Nvidia's path tracing repository, which is shown at Nvidia's RTX kit webpage , is https://github.com/NVIDIA-RTX/RTXPT .