I'm copying ls here because we don't really need the 'B' for bytes to be
listed every time. I think it looks better the new way. Unlike ls, don't
list directory sizes, because I've never found the pseudo-sizes they get
given at all useful.

Also, fix a bug where aligning columns didn't work when the number of
format characters (like '\x1B' and '[') were different between each
line.

See https://github.com/mozilla/rust/pull/14310

Also, reverse the way columns are rendered: before, a column took a stat and a name to render; now, a file takes a column type to render. This means that most of the File data/methods can be private.