Book: Finish tutorial

[killercup]

Issue tracking progress of tutorial chapters

• Project setup
  • [x] draft
  • [x] template: #53
  • [x] final review
• Parsing command line arguments
  • [x] draft
  • [x] clap 3: #64
  • [x] final review
• First implementation
  • [x] draft
  • [x] first revision
  • [x] final review
• Nicer error reporting
  • [x] draft
  • [x] error context, failure: #65
  • [x] final review
• Output for humans and machines
  • [x] draft
  • [x] stderr #66
  • [x] progress bars #67
  • [x] logging #68
  • [x] final review
• Testing
  • [x] draft
  • [x] writing testable code #71
  • [x] assert_cli #72
  • [x] final review
• Packaging and distributing
  • [x] draft
  • [x] packaging #69
  • [x] man pages (also shell completions) #70
  • [x] final review

[killercup]

further refinements in more specific issues