### Breaking changes

`Tree.iterate` no longer allows returning from inside the iteration (use cursors directly for that kind of use cases).

`Subtree` has been renamed to `SyntaxNode` and narrowed in scope a little.

The `top`, `skipped`, and `error` node props no longer exist.

### New features

The package now offers a `TreeCursor` abstraction, which can be used for both regular iteration and for custom traversal of a tree.

`SyntaxNode` instances have `nextSibling`/`prevSibling` getters that allow more direct navigation through the tree.

Node types now expose `isTop`, `isSkipped`, `isError`, and `isRepeated` properties that indicate special status.

Adds `NodeProp.group` to assign group names to node types.

Syntax nodes now have helper functions `getChild` and `getChildren` to retrieve direct child nodes by type or group.

`NodeType.match` (and thus `NodeProp.add`) now allows types to be targeted by group name.

Node types have a new `is` method for checking whether their name or one of their groups matches a given string.