add radial scale with tests

[heckj]

resolves #5

[codecov]

Codecov Report

Merging #15 (94dfdbd) into main (e888cb1) will increase coverage by 0.00%.
The diff coverage is 90.47%.

@@           Coverage Diff            @@
##             main      #15    +/-   ##
========================================
  Coverage   91.48%   91.48%            
========================================
  Files          25       27     +2     
  Lines        2101     2256   +155     
========================================
+ Hits         1922     2064   +142     
- Misses        179      192    +13     

Impacted Files	Coverage Δ
Sources/SwiftVizScale/ContinuousScale.swift	100.00% <ø> (ø)
Sources/SwiftVizScale/AnyContinuousScale.swift	61.66% <50.00%> (-3.15%)	⬇️
Sources/SwiftVizScale/RadialScale.swift	90.19% <90.19%> (ø)
Sources/SwiftVizScale/LinearScale.swift	98.03% <100.00%> (ø)
Sources/SwiftVizScale/LogScale.swift	92.30% <100.00%> (ø)
Sources/SwiftVizScale/PowerScale.swift	91.37% <100.00%> (ø)
Tests/SwiftVizScaleTests/RadialScaleTests.swift	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update e888cb1...94dfdbd. Read the comment docs.