When I was working on some column printing code
with Unicode I got bit by using `str::len`...and
digging in I found that clippy actually just
merged a lint to go the *other* way; more in
the link in the code.
Turning on a lint showed one place that should
have been using `chars().count()` and one that
should have been validating ASCII. Fix those.
Signed-off-by: Colin Walters <walters@verbum.org>
