Implement struct-of-arrays (SoA) utilities

[Ogeon]

This adds a set of iterators and utilities for converting between arrays of structs and structs of arrays. There's definitely more that can be done, but it's a start. This pull request includes:

• Creating and extendingColorType<Collection<T>> from any IntoIterator<Item=ColorType<T>>.
• Iterating over ColorType<Collection<T>>.
• Some Vec functions are available for ColorType<Vec<T>>, with more that can be added.
• Slicing and indexing with get and get_mut.
• Working with ColorType<&T> and ColorType<&mut T>, using copied, cloned and set.

See the discussion in #303 for some background.

Closed Issues

• Closes Pixel to Struct of Arrays (and back again!) #305.

[Ogeon]

There are still a few pieces left, but it's time to stop for today.

[github-actions]

Benchmark for da49fc0

Click to view benchmark

Test	Base	PR	%
Cie family/lab to lch	3.2±0.10µs	3.2±0.07µs	0.00%
Cie family/lab to xyz	760.9±17.06ns	763.5±15.99ns	+0.34%
Cie family/lch to lab	2.4±0.03µs	2.4±0.08µs	0.00%
Cie family/linsrgb to xyz	308.0±4.47ns	310.2±9.66ns	+0.71%
Cie family/linsrgb to xyz - wide::f32x8	101.7±1.28ns	107.2±1.25ns	+5.41%
Cie family/xyz to lab	18.0±0.51µs	18.1±0.48µs	+0.56%
Cie family/xyz to yxy	628.7±7.77ns	629.6±8.44ns	+0.14%
Cie family/yxy to xyz	653.2±18.92ns	653.3±13.12ns	+0.02%
Matrix functions/matrix_inverse	11.1±0.14ns	10.7±0.14ns	-3.60%
Matrix functions/multiply_3x3	9.8±0.94ns	9.7±0.14ns	-1.02%
Matrix functions/multiply_rgb_to_xyz	6.0±0.08ns	6.0±0.09ns	0.00%
Matrix functions/multiply_xyz	6.0±0.12ns	6.0±0.13ns	0.00%
Matrix functions/multiply_xyz_to_rgb	6.0±0.09ns	6.0±0.09ns	0.00%
Matrix functions/rgb_to_xyz_matrix	24.9±0.37ns	24.9±0.31ns	0.00%
Rgb family/hsl to hsv	649.9±7.29ns	650.9±7.54ns	+0.15%
Rgb family/hsl to linear hsl	13.0±0.24µs	13.0±0.23µs	0.00%
Rgb family/hsl to rgb	2.2±0.03µs	2.2±0.03µs	0.00%
Rgb family/hsv to hsl	821.8±19.35ns	822.3±10.23ns	+0.06%
Rgb family/hsv to hwb	233.4±3.88ns	233.9±2.99ns	+0.21%
Rgb family/hsv to linear hsv	11.7±0.14µs	11.8±0.30µs	+0.85%
Rgb family/hsv to rgb	1921.7±41.53ns	1972.9±28.58ns	+2.66%
Rgb family/hwb to hsv	482.0±11.03ns	482.3±6.80ns	+0.06%
Rgb family/hwb to linear hwb	12.4±0.17µs	12.3±0.18µs	-0.81%
Rgb family/linear hsl to hsl	11.3±0.22µs	11.3±0.18µs	0.00%
Rgb family/linear hsv to hsv	10.4±0.31µs	10.2±0.14µs	-1.92%
Rgb family/linear hwb to hwb	11.3±0.19µs	11.3±0.19µs	0.00%
Rgb family/linsrgb to rgb	5.9±0.17µs	5.9±0.08µs	0.00%
Rgb family/linsrgb to rgb - wide::f32x8	5.1±0.09µs	5.1±0.06µs	0.00%
Rgb family/linsrgb_f32 to rgb_u8	959.4±13.80ns	961.9±14.36ns	+0.26%
Rgb family/linsrgb_f64 to rgb_u8	1217.8±13.21ns	1219.0±18.57ns	+0.10%
Rgb family/rgb to hsl	848.4±13.67ns	855.3±13.01ns	+0.81%
Rgb family/rgb to hsl - wide::f32x8	472.1±8.08ns	469.8±6.49ns	-0.49%
Rgb family/rgb to hsv	515.3±9.63ns	523.1±6.03ns	+1.51%
Rgb family/rgb to hsv - wide::f32x8	426.9±4.69ns	428.3±7.82ns	+0.33%
Rgb family/rgb to linsrgb	8.3±0.11µs	8.3±0.20µs	0.00%
Rgb family/rgb to linsrgb - wide::f32x8	3.3±0.07µs	3.3±0.08µs	0.00%
Rgb family/rgb_u8 to linsrgb_f32	307.9±6.14ns	306.8±4.89ns	-0.36%
Rgb family/rgb_u8 to linsrgb_f64	311.2±3.25ns	312.7±4.92ns	+0.48%
Rgb family/xyz to linsrgb	355.4±6.12ns	354.0±5.61ns	-0.39%
Rgb family/xyz to linsrgb - wide::f32x8	105.5±1.47ns	106.2±2.50ns	+0.66%

[Ogeon]

I believe this fulfills the initial requirements and some more. 🙂 I struggled a bit with coming up with a good example, so that may be improved later.

[github-actions]

Benchmark for b1e0c79

Click to view benchmark

Test	Base	PR	%
Cie family/lab to lch	3.2±0.04µs	3.2±0.08µs	0.00%
Cie family/lab to xyz	764.9±9.22ns	764.8±14.05ns	-0.01%
Cie family/lch to lab	2.4±0.05µs	2.4±0.05µs	0.00%
Cie family/linsrgb to xyz	308.8±7.12ns	310.6±7.19ns	+0.58%
Cie family/linsrgb to xyz - wide::f32x8	101.1±1.90ns	101.7±2.33ns	+0.59%
Cie family/xyz to lab	17.9±0.26µs	18.3±1.10µs	+2.23%
Cie family/xyz to yxy	632.8±10.08ns	629.8±14.93ns	-0.47%
Cie family/yxy to xyz	547.4±7.70ns	548.2±7.47ns	+0.15%
Matrix functions/matrix_inverse	10.7±0.15ns	10.8±0.22ns	+0.93%
Matrix functions/multiply_3x3	9.7±0.28ns	9.6±0.11ns	-1.03%
Matrix functions/multiply_rgb_to_xyz	6.0±0.08ns	6.0±0.12ns	0.00%
Matrix functions/multiply_xyz	6.0±0.15ns	6.0±0.18ns	0.00%
Matrix functions/multiply_xyz_to_rgb	6.0±0.06ns	6.0±0.11ns	0.00%
Matrix functions/rgb_to_xyz_matrix	24.9±0.37ns	24.9±0.34ns	0.00%
Rgb family/hsl to hsv	649.7±9.86ns	648.3±8.63ns	-0.22%
Rgb family/hsl to linear hsl	13.2±0.21µs	13.1±0.30µs	-0.76%
Rgb family/hsl to rgb	2.1±0.02µs	2.1±0.04µs	0.00%
Rgb family/hsv to hsl	831.4±37.51ns	821.2±11.13ns	-1.23%
Rgb family/hsv to hwb	233.4±4.67ns	233.0±4.51ns	-0.17%
Rgb family/hsv to linear hsv	11.7±0.13µs	11.8±0.21µs	+0.85%
Rgb family/hsv to rgb	1968.5±49.27ns	1915.3±26.59ns	-2.70%
Rgb family/hwb to hsv	479.7±4.65ns	482.8±15.01ns	+0.65%
Rgb family/hwb to linear hwb	12.4±0.27µs	12.4±0.19µs	0.00%
Rgb family/linear hsl to hsl	11.2±0.18µs	11.2±0.17µs	0.00%
Rgb family/linear hsv to hsv	10.2±0.14µs	10.3±0.15µs	+0.98%
Rgb family/linear hwb to hwb	11.3±0.16µs	11.3±0.16µs	0.00%
Rgb family/linsrgb to rgb	5.9±0.11µs	5.9±0.22µs	0.00%
Rgb family/linsrgb to rgb - wide::f32x8	5.2±0.10µs	5.2±0.12µs	0.00%
Rgb family/linsrgb_f32 to rgb_u8	959.3±15.55ns	954.8±17.43ns	-0.47%
Rgb family/linsrgb_f64 to rgb_u8	1225.0±31.96ns	1221.8±27.84ns	-0.26%
Rgb family/rgb to hsl	853.4±13.86ns	847.9±11.22ns	-0.64%
Rgb family/rgb to hsl - wide::f32x8	469.7±6.94ns	470.2±7.51ns	+0.11%
Rgb family/rgb to hsv	516.7±20.28ns	515.1±13.27ns	-0.31%
Rgb family/rgb to hsv - wide::f32x8	430.0±7.44ns	431.6±12.26ns	+0.37%
Rgb family/rgb to linsrgb	8.3±0.14µs	8.3±0.17µs	0.00%
Rgb family/rgb to linsrgb - wide::f32x8	3.3±0.05µs	3.3±0.05µs	0.00%
Rgb family/rgb_u8 to linsrgb_f32	306.2±3.71ns	306.8±4.33ns	+0.20%
Rgb family/rgb_u8 to linsrgb_f64	311.3±3.66ns	312.1±3.25ns	+0.26%
Rgb family/xyz to linsrgb	352.8±4.07ns	354.3±7.63ns	+0.43%
Rgb family/xyz to linsrgb - wide::f32x8	106.1±1.54ns	105.6±1.55ns	-0.47%

[Ogeon]

bors r+

[bors]

Build succeeded:

• ci