* Lookup uname/gname if not provided by the archive (I copied the
uname/gname lookup cache from bsdtar)
* Format device number instead of size for device nodes
* Format date.
There's still a few improvements that I could copy from
bsdtar, especially the locale-aware safe_fprintf() code
and the locale-aware setup for day_first date formatting.
(And, of course, I need to think through a clean way to
push this stuff down into libarchive.)
Thanks to Peter Wemm for reminding me of this overlooked TODO item.