5.1.0

• Preliminary i18n implementation (#2140).
• Expose URL with auth token in notebook UI (#2666).
• Fix search background style (#2387).
• List running notebooks without requiring --allow-root (#2421).
• Allow session of type other than notebook (#2559).
• Fix search background style (#2387).
• Fix some Markdown styling issues (#2571), (#2691) and (#2534).
• Remove keymaps that conflict with non-English keyboards (#2535).
• Add session-specific favicons (notebook, terminal, file) (#2452).
• Add /api/shutdown handler (#2507).
• Include metadata when copying a cell (#2349).
• Stop notebook server from command line (#2388).
• Improve “View” and “Edit” file handling in dashboard (#2449) and (#2402).
• Provide a promise to replace use of the app_initialized.NotebookApp event (#2710).
• Fix disabled collapse/expand output button (#2681).
• Cull idle kernels using --MappingKernelManager.cull_idle_timeout (#2215).
• Allow read-only notebooks to be trusted (#2718).

See the 5.1 milestone on GitHub for a complete list of issues and pull requests involved in this release.