Don't use \n sequence inside Lisp strings needing translation...

... Because xgettext will just remove the \, not replace \n with newline.

That's consistent with Lisp reader behavior in this documentation:
http://www.lispworks.com/documentation/lw70/CLHS/Body/02_de.htm

The XLisp reader, which replaces \n with newline, is nonstandard.

So, to accommodate xgettext, use (format nil "...~%...") instead, or where
you can't do that in a $ header line, just make a line break inside the ""

There are a few "\n" left alone in sample-data-export.ny which are neither
in $ lines nor inside (_ "...")

plug-ins/SpectralEditMulti.ny

@@ -62,5 +62,5 @@ $copyright (_"Released under terms of the GNU General Public License version 2")
                (prod (diff 1.0 env) sig))))))
 
 (catch 'error-message
-  (setf p-err (_"Error.\n"))
+  (setf p-err (format nil (_"Error.~%")))
   (multichan-expand #'result *track*))