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

[Stefan Monnier]

>> I think the issue here is whether we want to "render" the text, or
>> whether we want to show the file's content to the user.
> Isn't whitespace-mode for showing the content, as far as spaces
> are concerned?

whitespace mode is good at showing where you have things like
trailing-spaces, but other than anal retentive guys like us,
nobody cares.  OTOH many people (myself included) have wasted hours
tracking bugs where some chunk of code contained some weird char like
a NBSP that displayed exactly like a normal space but isn't parsed the
same way.

For similar reasons, we don't treat ~ in TeX as whitespace: while its
rendering will display as whitespace its meaning in the source code is
non-trivial.

I'm aware that neither ~ in TeX nor NBSP are quite the same as the
problem at hand, but there is still the same general issue of
distinguishing the specification from its rendering and when editing
a file in Emacs you often what to see what the file specifies more than
what it will render to (which you'll want to see maybe elsewhere such
as in a browser).


        Stefan