Use single dash for year spans in ly

Randhartinger_AdTeLevavi_Settings_Global.ily

@@ -7,7 +7,7 @@ scorenumber="EK-0057"
 \header {
   title = "Ad te levavi"
   subtitle = "Offertorium"
-  composer = "Benedict Randhartinger (1802--1893)"
+  composer = "Benedict Randhartinger (1802-1893)"
   arranger = "Bearbeitung: Roman Zäch"
   copyright = \markup \abs-fontsize #9 \column{
       \line { "2010, " \concat{\with-url #"http://www.edition-kainhofer.com/" {Edition Kainhofer, Vienna},} \concat{\scorenumber.} "Alle Rechte vorbehalten / All rights reserved / Printed in Austria."}