added ProofContext.pprint_context (depends on ProofContext.debug);

--- a/src/Pure/install_pp.ML	Fri Jan 27 19:03:02 2006 +0100
+++ b/src/Pure/install_pp.ML	Fri Jan 27 19:03:05 2006 +0100
@@ -8,5 +8,6 @@
 install_pp (make_pp ["Thm", "cterm"] Display.pprint_cterm);
 install_pp (make_pp ["Thm", "ctyp"] Display.pprint_ctyp);
 install_pp (make_pp ["Context", "theory"] Context.pprint_thy);
+install_pp (make_pp ["Context", "proof"] ProofContext.pprint_context);
 install_pp (make_pp ["Syntax", "ast"] Syntax.pprint_ast);
 install_pp (make_pp ["typ"] (Sign.pprint_typ ProtoPure.thy));