### Breaking changes

`Parser.group` is now called `Parser.nodeSet`.

Nested parsers now work differently. They don't have to be Lezer parsers, but have to produce object conforoming to the `PartialParse` interface. The interface with which non-trivial nested parsers are specified also changed—see the `NestedParser` type.

Parser objects no longer have a `topType` property (scan their node set for types with `isTop` set instead).

`Parser` objects no longer have `withProps`, `withNested`, and `withTokenizer` methods (use `configure` instead).

Both `Parser.parse` and `Parser.startParse` now take an optional start position as second parameter and an optional parse context as third. `startParse` returns an instance of the `PartialParse` interface instead of the old `ParseContext` class (whose name is now used for something else). Parse _options_ are no longer passed to these methods, but configured in advance through `Parser.configure`.

During incremental parsing, instead of passing a tree as the `cache` option, reusable subtrees (see `TreeFragment` from lezer-tree) are now retrieved from the `fragments` property of the parse context object, if provided.

`Parser.parse` and `Parser.startParse` no longer take an options parameter. Instead, `bufferLength` and `strict` can be configured with `Parser.configure` now, and the start position and context are passed as optional arguments.

The `InputStream` type has been replaced by `Input` from the lezer-tree package (which has the same interface but a more appropriate name).

### New features

The `Parser` class now has a `configure` method that is used to create a parser instance with a more specific configuration.