Vulkan implementation of radiance cascades for global illumination. https://www.youtube.com/watch?v=lpKE0YDOlZA
- Lower vulkan minimum capabilities (especially shader constant size 8 and 16, as it seems it is not supported by many gpus)
- Fix radiance cascade merging which is probably the cause for weird checkerboard pattern (more noticeable on lower cascade resolution)
- Code cleanup