Borgmatic

* 140: List the files within an archive via --list --archive option.

* 119: Include a sample borgmatic configuration file in the documentation.
* 123: Support for Borg archive restoration via borgmatic --extract command-line flag.
* Refactor documentation into multiple separate pages for clarity and findability.
* Organize options within command-line help into logical groups.
* Exclude tests from distribution packages.

* 127: Remove date echo from schema example, as it's not a substitute for real logging.
* 132: Leave exclude_patterns glob expansion to Borg, since doing it in borgmatic leads to
confusing behavior.
* 136: Handle and format validation errors raised during argument parsing.
* 138: Allow use of --stats flag when --create or --prune flags are implied.

* 103: When generating sample configuration with generate-borgmatic-config, document the defaults
for each option.
* 116: When running multiple configuration files, attempt all configuration files even if one of
them errors. Log a summary of results at the end.
* Add borgmatic --version command-line flag to get the current installed version number.

* 100: Support for --stats command-line flag independent of --verbosity.
* 117: With borgmatic --init command-line flag, proceed without erroring if a repository already
exists.

* 110: Support for Borg repository initialization via borgmatic --init command-line flag.
* 111: Update Borg create --filter values so a dry run lists files to back up.
* 113: Update README with link to a new/forked Docker image.
* Prevent deprecated --excludes command-line option from being used.
* Refactor README a bit to flow better for first-time users.
* Update README with a few additional borgmatic packages (Debian and Ubuntu).