atool with support for zstd
Given that the last release of atool is from 2012, and that the maintainer is not reachable, I have created this "fork" to bring support for zstd into atool.
For an actively maintained port, look at patool (in python). For a lua port, look at satool.
Don't expect me to add features or anything fancy, except new format support. To be honest, I don't know how to write perl code.