more build options;

--- a/etc/options	Thu Jul 26 19:40:19 2012 +0200
+++ b/etc/options	Thu Jul 26 19:41:05 2012 +0200
@@ -27,6 +27,8 @@
 declare names_short : bool = false
 declare names_unique : bool = true
 
+declare pretty_margin : int = 76
+
 declare thy_output_display : bool = false
 declare thy_output_quotes : bool = false
 declare thy_output_indent : int = 0

--- a/src/Pure/System/build.ML	Thu Jul 26 19:40:19 2012 +0200
+++ b/src/Pure/System/build.ML	Thu Jul 26 19:41:05 2012 +0200
@@ -40,6 +40,7 @@
     |> Unsynchronized.setmp Thy_Output.indent_default (Options.int options "thy_output_indent")
     |> Unsynchronized.setmp Thy_Output.source_default (Options.bool options "thy_output_source")
     |> Unsynchronized.setmp Thy_Output.break_default (Options.bool options "thy_output_break")
+    |> Unsynchronized.setmp Pretty.margin_default (Options.int options "pretty_margin")
     |> Unsynchronized.setmp Toplevel.timing (Options.bool options "timing");
 
 fun use_theories (options, thys) =