Update book 1 renders plus many listing fixes

- Reduced code duplication in dielectric::scatter()
- Change standard render dimensions to 400x225
- Change image 6 to a before-and-after pair to show antialiasing
- Refactored material and geometry declarations (multiple listings)
- Refactored assignment of `etai_over_etat`
- Fix multiple listing highlighting misses
- Fix multiple listing include errors
- Add missing `double t` member of struct `hit_record`
- Add missing scene code changes at various points
- Show final scene render parameters plus highlighting

See #179
Resolves #547
Resolves #548
Resolves #549
Resolves #550
Resolves #551
Resolves #552
Resolves #553
Resolves #554
Resolves #555
Resolves #556
Resolves #557
Resolves #560
Resolves #561
Resolves #562
Resolves #563
Resolves #564
Resolves #565
Resolves #566

CHANGELOG.md

@@ -5,11 +5,37 @@ Change Log -- Ray Tracing in One Weekend
 
 ### Common
   - Change: Renamed and explicitly numbered book images and figures (#495)
+  - Fix: Reduced code duplication in dielectric::scatter() function
   - New: Added alternative constructors that take color arguments in addition to the constructors
     that take `shared_ptr<texture>` arguments, simplifying calling code. This applies to the
     following classes: `checker_texture`, `constant_medium`, `diffuse_light`, and `lambertian`.
     (#516)
 
+### _In One Weekend_
+  - Change: Updated all rendered images except for 1.13, 1.14 (#179, #547, #548, #549, #550, #551,
+    #552, #553, #554, #555, #556, #557, #560, #561, #562, #563, #564, #565, #566)
+  - Change: Standard render width changed to 400
+  - Change: Image 6 is now a before-and-after pair to illustrate antialiasing
+  - Change: Listing 48: Refactored material and geometry declarations
+  - Change: Listing 52: Refactored assignment of `etai_over_etat`
+  - Change: Listing 56: Refactored material declarations
+  - Change: Listing 61: Refactored material and geometry declarations
+  - Fix: Corrected various missed change highlights in code listings
+  - Fix: Listing 7: Added missing `color.h`, `vec3.h` includes
+  - Fix: Listing 18: Add missing `double t` member of struct `hit_record`
+  - Fix: Listing 24: Add missing `color.h` include
+  - Fix: Listing 30: Add missing `camera.h` include
+  - Fix: Listing 42: Don't need to include `ray.h` when using `rtweekend.h`
+  - Fix: Listing 48: Add missing `material.h` include
+  - Fix: Listing 61: Include updated `cam` declaration, show context w/highlighting
+  - Fix: Listing 63: Show reverted scene declarations
+  - Fix: Listing 68: Show final scene render parameters with highlighting
+  - New: Listing 50: Show the updated material definitions
+
+### _The Next Week
+
+  - Fix: Listing 7: Show reverted viewing parameters from book 1 final scene
+
 
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 # v3.1.2 (in progress)