- Add colorization of options, choices and metavars in help screens.
- Add `--color`/`--no-color` option flag (aliased to `--ansi`/`--no-ansi`).
- Add colored `--version` option.
- Add colored `--verbosity` option and logs.
- Add dependency on `click-log`.
- `--time`/`--no-time` flag to measure duration of command execution.
- Add platform recognition utilities.
- Add new conditional markers for `pytest`: `skip_{linux,macos,windows}`,
`unless_{linux,macos,windows}`, `destructive` and `non_destructive`.