v2.5

This release adds the ability to easily extend the library, thanks to two improvements: looser coupling between charts and the library's core code, and the introduction of hooks. These changes are due to the wonderful work of @dandehavilland.

For an overview of the changes, have a read through this page. You can see a sample addon in action on the examples page.

Please refer to the 2.5 milestone for a complete list of changes and bug fixes.

Thanks to @dstaley, @dubek and @dandehavilland for contributions to this release.