Upgrade to jfreechart-builder v1.5.6

Minor patch update to upgrade to jfreechart-builder v1.5.6

Patch to incorporate jfreechart-builder bugfixes

Merge pull request #20 from matoos32/develop

Merge develop into main

Patch to incorporate jfreechart-builder bugfixes

• Fix no y-axis label on generic time series plots
• Fix ChartBuilder not properly guarding array indexing into timeData

Gapless time series charts

• Extract method refactorings to facilitate coping sample code to README files.
• Add ability to remove time gaps in time series charts.

Plot colors, y-axis number formatting, and Javadoc

• Add ability to specify plot colors and toggle grid lines.
• Add ability to specify y-axis tick number formatting.
• Add missing Javadoc to various parts of the code.
• Improve the README.

XYAnnotation support and shortened interface methods

• Added support for building XYAnnotation instances
• Integrate a breaking change to rename some interface methods to shorten their names

Initial demo app

Merge pull request #1 from matoos32/initial-demo-app

Implement initial demo app with some documentation