[Feature] (Full) XCI and XCZ support

[alucryd]

Opening a dedicated issue so I can keep track of this. nsz doesn't support Full XCI yet, neither does it reversible XCZ compression. Hopefully that will change in the near future. I just submitted a PR to support compressing Full XCI dumps, now it's up to me or the author to tackle reversible compression. My time is quite a bit limited these days so I hope the author can have a crack at it.

[alucryd]

Good news, my PR has been merged a while ago, and upstream is making good progress towards reversible XCZ so this might be around the corner :)