bug#13399: 24.3.50; Word-wrap can't wrap at zero-width space U-200B

[martin rudalics]

> You can insert invisible text in between the characters, such as
>
>     (propertize " " 'invisible t)

One could also use display properties or overlays.  But zero-width
spaces can be easily saved to file and read back (not that this is
something I'd need in the case at hand).

martin