Martin von Zweigbergk dd4c47f373 tree: support filtering diff by matcher
This change teaches `Tree::diff()` to filter by a matcher. It only
filters the result so far; it does not restrict the tree walk to what
`Matcher::visit()` says is necessary yet. It also doesn't teach the
CLI to create a matcher and pass it in.
2021-06-09 16:26:58 -07:00
..