unicode no-break spaces

[Karl Berry]

Patrice,

BTW, I was just reminded of something you probably already well knew:
Unicode has both breaking and non-breaking thin spaces, U+2009 and
U+202F (and presumably others, I didn't check).  That makes a lot more
sense than just a breaking thin space.

So for texi2any purposes, it's important that we only break at those
spaces listed in http://www.unicode.org/reports/tr14/ ...

Thanks,
Karl