Kthresher

Added
- Support for nested config files through `include` setting.
- README info about how a package is marked for autoremoval.
- README info to be able to perform tests by installing kernels and headers.

Changed
- Default config file to only include a `include` path for `/etc/kthresher.d/*.conf`

Removed
- Debian dir and drone configs, will not live now with the code, thebwt will maintain that now.
- Config file support for dry-run, this is now only available through command line arguments.

Added
- Drone config.

Changed
- Debian configs for proper building.

Fixed
- Typos on man page.

Added
- Man page.
- Changelog.
- Debian directory for .debs.

Changed
- Flatten directory structure for .deb.
- Cron file to check if script is available prior execution.

Added
- Cron file cron.daily.

Added
- Support for old virtual kernel packages.

Fixed
- Bug when searching for a list of installed kernel images.

Added
- Support to remove headers '-h'.