* rename archive -> arcfile (where it's a file descriptor)
* additional return
* simplify logic around 'archive?' flag
* maintain os separator after arcroot
* use function instead of lambda for filter, ensure file exists before file.cmp'ing it
* track errored files and fail if there are any
* Don't include the archive in the archive if it falls within an archived path
* If remove=True and the archive would be in an archived path, fail.
* Fix single-file zip file compression
* Add more documentation about 'state' return
This manages compressed files or archives of many compressed files. You can maintain or update .gz, .bz2 compressed files, .zip archives, or tarballs compressed with gzip or bzip2.
Possible use cases:
* Back up user home directories
* Ensure large text files are always compressed
* Archive trees for distribution