### Breaking changes

When multiple highlight styles are available in an editor, they will be combined, instead of the highest-precedence one overriding the others.

`HighlightStyle.define` now expects an array, not a variable list of arguments.

### New features

Highlight styles now have a `fallback` property that installs them as a fallback highlighter, which only takes effect if no other style is available.

It is now possible to map style tags to static class names in `HighlightStyle` definitions with the `class` property.

The new `classHighlightStyle` assigns a set of static classes to highlight tags, for use with external CSS.

Highlight styles can now be scoped per language.