Breaking changes
`ResolvedPos.sameDepth` is now called [`ResolvedPos.sharedDepth`](https://prosemirror.net/docs/ref/version/0.13.0.html#model.ResolvedPos.sharedDepth), and takes a raw, unresolved position as argument.
New features
[`DOMSerializer`](https://prosemirror.net/docs/ref/version/0.13.0.html#model.DOMSerializer)'s `nodes` and `marks` properties are now public.
[`ContentMatch.findWrapping`](https://prosemirror.net/docs/ref/version/0.13.0.html#model.ContentMatch.findWrapping) now takes a third argument, `marks`. There's a new method [`findWrappingFor`](https://prosemirror.net/docs/ref/version/0.13.0.html#model.ContentMatch.findWrappingFor) that accepts a whole node.
Adds [`Slice.maxOpen`](https://prosemirror.net/docs/ref/version/0.13.0.html#model.Slice^maxOpen) static method to create maximally open slices.
DOM parser objects now have a [`parseSlice`](https://prosemirror.net/docs/ref/version/0.13.0.html#model.DOMParser.parseSlice) method which parses an HTML fragment into a [`Slice`](https://prosemirror.net/docs/ref/version/0.13.0.html#model.Slice), rather than trying to create a whole document from it.