added symbol_font.ML;

--- a/src/Pure/Syntax/ROOT.ML	Mon Nov 18 17:28:40 1996 +0100
+++ b/src/Pure/Syntax/ROOT.ML	Mon Nov 18 17:29:05 1996 +0100
@@ -5,6 +5,7 @@
 This file builds the syntax module.
 *)
 
+use "symbol_font.ML";
 use "pretty.ML";
 use "lexicon.ML";
 use "ast.ML";