bug#10016: ls -lk is wrong

[Paul Eggert]

The long option shouldn't be --kilobyte, since ls -k means
1024 not 1000.  So I suppose it should be --kibibyte.

It's a little tricky, since -k means --block-size=1K
for df and du as well, and I assume this won't change,
since df -k and du -k conform to POSIX. (Surely there's
no need to add --kibibyte to du and df -- why should
we make df and du more confusing merely because
ls must be more confusing? :-).

So does the following sound plausible?

Add --kibibyte to 'ls', make it equivalent to -k, change
-k so that it conforms to POSIX, and have --block-size
override -k.  But leave df and du alone