@rlsrnamed{Name,Translation} translates also the name in the URI

[Federico Bruni]

Issue 1721 reported that @rlsr{Name} keeps the text in english but 
translates the link in the translated manuals (no idea where the 
translation comes from).
So it recommends to use @rlsrnamed{Name,Translation} instead.

But it looks like @rlsrnamed is affected by the same bug.

Looking through the log file of make doc I've found a lot of errors like 
this:

WARNING: Unable to find node 'Hauteurs' in book snippets.

(look at NR 1.1, you'll find a lot of these broken links)

In general, go to the french NR and search for "Morceaux choisis :": 
you'll see that most of the links are broken.

There are some exceptions, for example this works:
http://lilypond.org/doc/v2.15/Documentation/notation/piano.fr.html

(Claviers link down on the page)

The syntax used is the same: @rlsrnamed{Name,Translation}.
Putting a space after the comma makes any difference.

I can't understand the reason of this weird behaviour.
Can you please explain what's happening?

Thanks,
Federico