etc/settings

--- a/etc/settings	Wed Nov 07 14:06:43 2018 +0100
+++ b/etc/settings	Wed Nov 07 21:42:16 2018 +0100
@@ -20,6 +20,8 @@
 
 classpath "$ISABELLE_HOME/lib/classes/Pure.jar"
 
+isabelle_file_format 'isabelle.Bibtex$File_Format'
+
 #paranoia settings -- avoid intrusion of alien options
 unset "_JAVA_OPTIONS"
 unset "JAVA_TOOL_OPTIONS"