Support more compression algorithms with GNU tar

[rotdrop]

Hi,

thank you for this nice library! looking at the existing GNU tar adapters it looks like adding more compression methods (--xz, --lzip, --lzma, --lzop, --zstd) would be extremely easy, at least if there are didicated file extensions (e.g. .tar.xz).

Is there a reason why those do not exist yet? Would pull request be welcome?

Thanks

Claus