Merge PR

Rules

1. Merge with a merge commit, not squash or rebase. Default to the current branch's PR.
2. Close linked issues still open. GitHub auto-closes them only for merges into the default branch. Skip if none.
3. Update partially addressed issues. For issues the PR references without closing (e.g. "fixes from #125"), check off the items it completed in the issue body and keep the issue open. Skip if none.
4. Delete the branch, remote and local.