Allows adding series to a chart with different chart types,
improving chart versatility.

The change refactors the chart series writing logic to iterate
through series grouped by type, generating the appropriate XML
structure for each type.

Implements the ability to style chart series individually
by introducing a new 'style' parameter to the `addSeries` method.

Adds options to show or hide the category and value axis lines,
enhancing chart customization.

Also includes a fix related to legend entries. It addresses an
issue where legend keys were not consistently displayed or hidden
based on data label options.

Adds functionality to customize chart elements, including line symbols, legend overlays, and gridline appearance.

This enhancement improves chart visual representation and allows for more detailed and informative data display. It also introduces options for displaying data labels, managing legend entries, and controlling gridline visibility.

Allows to disable category labels for charts by adding the 'none' option to the category label position enumeration.

Adds 'none' as a valid option for the chart value label position.
This enables hiding the value labels completely.

Adds an option to smooth the chart lines in the generated document. This improves the visual appearance of the charts, particularly line charts, by rendering them with smoother curves instead of jagged lines.

Implements functionality to format chart data labels and category axis labels.

This allows users to control the appearance of labels,
including font size, typeface, and format codes.

Ensures chart axis labels, both category and value,
display the correct format code, improving data
representation and readability in generated charts.