bug#11948: 24.1.50; word-wrap should allow wrapping at all breaking space characters, not just space and tab

[Eli Zaretskii]

> From: Reuben Thomas <rrt@sc3d.org>
> Date: Mon, 16 Jul 2012 13:42:18 +0100
> 
> I noticed this when in visual-line-mode, and it failed to wrap at an em
> space (U+2003), but of course there are lotsof other breaking space
> characters.

A prerequisite for doing something about this is to decide which
characters should allow breaking the line.  Is there some guidance in
the Unicode standard or elsewhere about this?  If not, we will have to
decide on our own.