Validate Book 1 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.

• [ ] 1.1: First PPM image
• [ ] 1.2: A blue-to-white gradient depending on ray Y coordinate
• [ ] 1.3: A simple red sphere
• [ ] 1.4: A sphere colored according to its normal vectors
• [ ] 1.5: Resulting render of normals-colored sphere with ground
• [ ] 1.6: Before and after anti aliasing
• [ ] 1.7: First render of a diffuse sphere
• [ ] 1.8: Diffuse sphere, with gamma correction
• [ ] 1.9: Correct rendering of Lambertian spheres
• [ ] 1.10: Rendering of diffuse spheres with hemispherical scattering
• [ ] 1.11: Shiny metal
• [ ] 1.12: Fuzzed metal
• [ ] 1.13: Glass first
• [ ] 1.14: Glass sphere that always refracts
• [ ] 1.15: Glass sphere that sometimes refracts
• [ ] 1.16: A hollow glass sphere
• [ ] 1.17: A wide-angle view
• [ ] 1.18: A distant view
• [ ] 1.19: Zooming in
• [ ] 1.20: Spheres with depth-of-field
• [ ] 1.21: Final scene

[hollasch]

Note to double check with #914