• NOTE: behaviour change. If a Dataset is made up of rows of maps, column_names now returns headers if it is supplied, otherwise returns map keys from the first row. Previously, it just returned the map keys from the first row.
• NOTE: PlotContent.get_svg_legend has been replaced with PlotContent.get_legend_scales. This moves the responsibility for legend rendering to Plot, which allows multiple scales to be combined in future. This change was needed to allow plot content to be resized based on the number of entries in the legend.
• Change smoothed line to round coordinates to 2 decimal places (reducing SVG size for large plots).
• Enable plot_options (show x axis, y axis) in LinePlot and PointPlot. Thanks @shadowRR
• Added meta to Dataset to allow carrying of handy information with the dataset.
• Added :legend_top and :legend_bottom options to :legend_settings - note that if you have too many legend entries it may push the plot content beyond the bottom of the plot.

• Add SimplePie - a sparkline-like Pie Chart. Thanks @zdenal.
• Add PieChart - a Pie Chart with more control over labels, colour palette, legend generation etc. Thanks @zdenal
• Add target option when setting BarChart event handler.
• Refactor BarChart to honour all options passed in new.
• Refactor PointPlot to honour all options passed in new.
• Refactor GanttChart to honour all options passed in new.
• Provide minimal default style so labels don't disappear unexpectedly if no CSS is set. Thanks @srowley.
• XML declaration added to generated SVG so the output can be served as an image. Thanks @srowley.
• Custom tick formatting enabled for PointPlot
• Added :custom_value_scale to BarChart to allow overriding of the automatically generated scale
• Added :custom_x_scale and :custom_y_scale to PointPlot to allow overriding of the automatically generated scales
• Added LinePlot (finally)
• Make stroke width for LinePlot adjustable through options. Thanks @littleStudent.
• Handle nil values in LinePlot by creating gaps in line.
• Stop crash on timescales when interval clashes with days in month resulting in invalid date. Thanks @imsoulfly.
• Fix colour palette option in GanttChart.

• Most of the options set via functions, e.g. BarChart.colours/2. Use the options in the relevant new functions instead.

• Allow Dataset to be created from a list of Maps (previously lists of lists and list of tuples were supported)
• Implement a data mapping mechanism to provide a consistent way of mapping data into required plot elements. Thanks @srowley for breaking the back of this.
• Added simplified chart creation API. Thanks @srowley. The existing API remains as-is
• Added test coverage for some components. Thanks @srowley
• Refactored SVG generation to minimise, or at least isolate, messy string interpolation, as per @elcritch suggestion. More to do on code tidy up.
• Improved Timescale code. Thanks for suggestions from Eiji
• Replaced Enum with Stream in (as yet to be activated) line generation code in PointPlot as per @elcritch suggestion.
• Fixed up some typespecs to stop Elixir 1.10 complaining. More to do to make the module struct specs right.
• Removed Timex dependency.
• A number of bug fixes in TimeScales, plus additional type guards
• Added basic sanitization of possible user inputs (titles, axis labels, category names from data). Sanitization approach is somewhat naive - basically any text is run through a copy of the Plug.HTML.html_escape.
• Fixed scaling bug in sparkline when data range was small
• Added axis_label_rotation option to PointPlot and BarChart. Thanks @srowley.
• Allow plot margins to be optionally specified and override default calcs. Thanks @axelson.

• Documentation for all modules
• Created type specs for the public API
• Renamed :data to :dataset in various plot types to avoid ambiguity
• ** BREAKING ** Renamed BarPlot to BarChart
• ** POTENTIALLY BREAKING ** Renamed ContinuousScale to ContinuousLinearScale, renamed constructor from new_linear() to new(). Used internally, so shouldn't cause any issues.
• ** POTENTIALLY BREAKING ** Made a number of margin calculation functions in Plot private. Shouldn't have been used externally anyway.
• ** POTENTIALLY BREAKING ** Removed set_x_range and set_y_range from PointPlot. No longer used as range is set by Plot size calcs.
• Fixed incorrect closed path in sparkline
• Allowed forcing of value range in BarChart (BarChart.force_value_range\2)
• Changed BarChart colour handling to pass through to ColourCategoryScale
• Changed new\3 to new\1 on various plots as width & height are now set by Plot
• Prevented infinite loop in ColourCategoryScale when setting palette to nil (turns out nil is an atom)
• Fixed divide by zero error in ContinuousLinearScale (needed to test for float as well as integer)
• Enabled legend for point plot
• Added multiple series for point plot (note - must share a common x value at this stage)

Initial version extracted from bigger project