Changes

• Improved support for flaming arrows and mobs (Iris only).
• Improved the visual quality of motion blur when temporal supersampling is enabled.
• Restored compatibility with older Minecraft versions in OptiFine (≤ 1.16.x) for non-NVIDIA GPUs.
• Began unifying the variable naming style in the shader code to make it clearer and less chaotic. More changes will follow in future versions.