Hi,

I've attached a patch that implements both "numeric sort" (-n) and "general
numeric sort" (-g).. I copied the relevant comparison code from sort.c to
ensure consistent behavior. Should these functions be extracted and put in
a shared header file, or is it okay to duplicate the code?

In terms of testing, I confirmed that the code correctly deals with
different single-byte thousand separators on my local machine, but I wasn't
sure how to exercise that in the test suite since I can't rely on everyone
having a particular locale available. How should that be handled?

I also updated the relevant docs.

Thanks,
Drew

P.S. I sent a previous version of the patch to the wrong address and
accidentally initiated a new bug thread (#10924). This patch supersedes the
previous.