Validate Book 2 Progression (Near End of v4 Development)

[hollasch]

After the messy merge of dev-patch (v3.2.2) into dev-minor and all of the work going on in v4, we should run through the book progression before v4 release.

Validate/update rendered images. Make sure that they are PNG format, and sized according to the rendered size specified in the code.

• [ ] 2.1: Bouncing spheres
• [ ] 2.2: Spheres on checkered ground
• [ ] 2.3: Checkered spheres
• [ ] 2.5: Earth-mapped sphere
• [ ] 2.6: White noise
• [ ] 2.7: White noise, blurred
• [ ] 2.8: Tiled random patterns
• [ ] 2.9: Hashed random texture
• [ ] 2.10: Perlin texture with trilinear interpolation
• [ ] 2.11: Perlin texture, trilinearly interpolated, smoothed
• [ ] 2.12: Perlin texture, higher frequency
• [ ] 2.13: Perlin texture, shifted off integer values
• [ ] 2.14: Perlin texture with turbulence
• [ ] 2.15: Perlin noise, marbled texture
• [ ] 2.16: Scene with rectangle light source
• [ ] 2.17: Scene with rectangle and sphere light sources
• [ ] 2.18: Empty Cornell box
• [ ] 2.19: Cornell box with two blocks
• [ ] 2.20: Standard Cornell box scene
• [ ] 2.21: Cornell box with blocks of smoke
• [ ] 2.22: Final scene