Fix bug in Oren-Nayar implementation
Fix bug in Oren-Nayar implementation

We now just match PBR's basically. Was having some odd bug with the
shading on the front of the sphere from a point light at certain
positions where it'd be darker than it should be

GuzTech/tray_rust,Twinklebear/tray_rust,voidException/tray_rust