Neater.
Use a scale function to calculate the x-position and width of bars.

Also switch from setting a pixel-value gap between bars to a percentage of a bar's width.
Add a way to visually check all test cases.
Use scale functions for the line chart.

This changes (actually fixes it) the axis placement slightly.
Expose the scale functions to the outside world.
Use a function to calculate the x/y position for a value/radius point on a circle.
Ensure bars are bottom-aligned when the chart is made up of positive values that are all the same.
Make it easier to see the SVG element's bounds when viewing all test cases.
More test cases on a single screen.
Some info on manually running the tests.
Diff will always be zero or more so it can be used as truthy.

Saves 11 bytes in the minified version!
Values passed to Array#concat don't need to be arrays.
Merge branch 'scale-functions'
Switch from passing a pie chart a diameter to passing it a radius.
Add a donut chart type.
It turns out you don’t need to specify Z to close a path.

Saves 12 bytes!
Ensure donut defaults can be changed independently to pie defaults.
Add docs for donut charts.
Merge branch 'donuts'
Remove the ability to read a chart’s options from its element’s data attributes.