v1.2 - Graduation Overhaul

To celebrate graduating from uni, I’ve overhauled this shader demo to improve several aspects:

• Simplified shader code
• More accurate vertex snapping
• Metal shader now uses single texture instead of cubemap
• Bug fixed lighting and environment fog
• Lighting mode set to Lambert instead of Lambert Wrap
• Banding & dithering is now performed as a post-process step rather than at the spatial level