wcwidth.c updated

I just updated

  http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c

with the following minor changes:

  - private use areas are now also in the ambiguous class (in accordance
    with the Unicode standard). [I made the same fix to the uniset
    package on http://www.cl.cam.ac.uk/~mgk25/download/uniset.tar.gz]

  - wcwidth is now called mk_wcwidth, etc., to avoid clashes with
    the glibc function wcwidth.

  - I significantly extended the comments.

Markus

-- 
Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org,  WWW: <http://www.cl.cam.ac.uk/~mgk25/>