proper init of cumulative settings;

--- a/lib/scripts/getsettings	Sun Aug 16 22:02:11 2020 +0200
+++ b/lib/scripts/getsettings	Mon Aug 17 12:35:03 2020 +0200
@@ -53,6 +53,11 @@
   unset CLASSPATH
 fi
 
+#init cumulative settings
+ISABELLE_FONTS=""
+ISABELLE_FONTS_HIDDEN=""
+ISABELLE_SCALA_SERVICES=""
+
 #main executables
 ISABELLE_TOOL="$ISABELLE_HOME/bin/isabelle"
 ISABELLE_SCALA_SCRIPT="$ISABELLE_HOME/bin/isabelle_scala_script"