Ray Tracing "The Rest of Your Life" - Final Chapter

• Added scattering_pdf Callable Programs to non-specular materials, fixing an issue from the previous release.
• Added Sphere_PDF and Buffer_PDF(similar to the hitable_list_pdf from the book. It's basically two buffers of different hitable PDFs(like rectangles)).
• Added a Hit_Record struct to the hitables and materials.
• Fixed scene functions.
• Added clamp to raygen.cu shader.
• Code cleanup.
• Release image, with a 1080x1080 resolution and 10kspp, took 55mins to render.