Fixes some of #256
This patch also cleans up the `icu` dependencies from my last PR. I
added all of `icu` as a dependency last time because I assumed it would
be needed for this fix. However, `chrono` supports localization and
`icu` seemed harder to use anyway.
Closes: #258
[lexical_sort](https://github.com/Aloso/lexical-sort) is currently
unmaintained. The author recommends switching to the `icu` crate which
is maintained by the Unicode Consortium.
