* add forwarding support in downloader
* Raise needed Go version to 1.21+ so slog can be used.
* Introduce validation mode flag (strict, unsafe)
* Add structured logging and place log into the download folder.
* Improve some code comment (bernhardreiter)
* Add counting stats to downloader.
* started with forwarding support in downloader
* Add missing files.
* Add missing files.
* Raise needed Go version
* More Go version bumping.
* Fix forwarding
* Go 1.21+ needed
* Make terminating forwarder more robust.
* Better var naming
* Remove dead code. Improve commentary.
* Prepare validation status adjustment.
* Move validations to functions to make them executable in a loop.
* Introduce validation mode flag (strict, unsafe)
* Use TOML as config file format.
* Parse command line a second time if config file was loaded.
* Handle default values correctly.
* Use same names for config file options and command line options.
* Add concurrent downloads to downloader.
* Moved to Go 1.20
* close files channel on producer side.
* Improve error handling
* New flag to ignore signature check results. Improve docs. Do not use number of CPUs to determine number of download workers.
* Set number of default workers in downloader to two.
