Overhaul to unify properties, add `CtSource` to prepare for Helix

[JeffFessler]

Make rays an iterator. Eliminate Unitful.Recipes

[codecov[bot]]

Codecov Report

Base: 99.63% // Head: 99.61% // Decreases project coverage by -0.02% :warning:

Coverage data is based on head (93acc4b) compared to base (e294313). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #29 +/- ## ========================================== - Coverage 99.63% 99.61% -0.03% ========================================== Files 24 31 +7 Lines 828 774 -54 ========================================== - Hits 825 771 -54 Misses 3 3 ``` | [Impacted Files](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | Coverage Δ | | |---|---|---| | [src/Sinograms.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL1Npbm9ncmFtcy5qbA==) | `100.00% <ø> (ø)` | | | [src/fbp2/back-fan.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2ZicDIvYmFjay1mYW4uamw=) | `97.95% <100.00%> (ø)` | | | [src/fbp2/back-par.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2ZicDIvYmFjay1wYXIuamw=) | `97.36% <100.00%> (ø)` | | | [src/fbp2/fbp.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2ZicDIvZmJwLmps) | `100.00% <100.00%> (ø)` | | | [src/fbp2/sino-plot.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2ZicDIvc2luby1wbG90Lmps) | `100.00% <100.00%> (ø)` | | | [src/fbp2/sino-weight.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2ZicDIvc2luby13ZWlnaHQuamw=) | `100.00% <100.00%> (ø)` | | | [src/fbp3/ct-plot.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2ZicDMvY3QtcGxvdC5qbA==) | `100.00% <100.00%> (ø)` | | | [src/geom/common.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2dlb20vY29tbW9uLmps) | `100.00% <100.00%> (ø)` | | | [src/geom/ct-geom.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2dlb20vY3QtZ2VvbS5qbA==) | `100.00% <100.00%> (ø)` | | | [src/geom/ct-source.jl](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None#diff-c3JjL2dlb20vY3Qtc291cmNlLmps) | `100.00% <100.00%> (ø)` | | | ... and [7 more](https://codecov.io/gh/JuliaImageRecon/Sinograms.jl/pull/29/diff?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None) | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=None)

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