nox 0.1.2

• nox updates itself: nox → Check for Updates…, the palette, the About window and Settings check
  GitHub Releases, then download, verify (SHA-256 + Developer ID signature) and install the
  update with a relaunch. A daily automatic check is on by default (app.check_for_updates).
• Quitting asks "Quit nox?" first, also when nothing is running; turn it off with
  app.confirm_quit (Settings → General). The window's close button hides nox; the
  Dock icon brings it back.