Set Line shapeRendering to crispEdges if rectilinear

[kmiyashiro]

Resolves cases where rectilinear lines on non-high DPI screens have an extra semi-opaque pixel added to the width because the line is set between pixels: #656

🚀 Enhancements

• Automatically set shapeRendering to crispEdges if rectilinear (completely horizontal or vertical).

I think this is the safest setting because using crispEdges on non-rectilinear lines may disable anti-aliasing, depending on the user agent.

https://developer.mozilla.org/en-US/docs/Web/SVG/Attribute/shape-rendering

crispEdges
This value indicates that the user agent shall attempt to emphasize the contrast between clean edges of artwork over rendering speed and geometric precision. To achieve crisp edges, the user agent might turn off anti-aliasing for all lines and curves or possibly just for straight lines which are close to vertical or horizontal. Also, the user agent might adjust line positions and line widths to align edges with device pixels.

[coveralls]

Pull Request Test Coverage Report for Build 288086819

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.05%) to 55.318%

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Totals
Change from base Build 283122090:	0.05%
Covered Lines:	1153
Relevant Lines:	2029

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💛 - Coveralls

[williaster]

amazing, thanks for the addition @kmiyashiro! 🙌 I agree the rectilinear dependency makes sense.