Features

• Added a new rc1 exercise.
• Added a new cow1 exercise.

Bug Fixes

• variables5: Corrected reference to previous exercise
• functions4: Fixed line number reference
• strings3: Clarified comment wording
• traits4, traits5: Fixed line number reference
• traits5:
  • Fixed typo in "parameter"
  • Made exercise prefer a traits-based solution
• lifetimes2: Improved hint
• threads3: Fixed typo in hint
• box1: Replaced unimplemented! with todo!
• errors5: Provided an explanation for usage of Box<dyn Error>
• quiz2: Fixed a typo
• macros: Updated the macros book link
• options1:
  • Removed unused code
  • Added more granular tests
• Fixed some comment syntax shenanigans in info.toml

Housekeeping

• Fixed a typo in .editorconfig
• Fixed a typo in integration_tests.rs
• Clarified manual installation instructions using cargo install --path .
• Added a link to our Zulip in the readme file