more practical time limit

--- a/src/HOL/Tools/res_atp.ML	Fri Jan 13 14:43:09 2006 +0100
+++ b/src/HOL/Tools/res_atp.ML	Fri Jan 13 17:39:03 2006 +0100
@@ -21,7 +21,7 @@
 
 val call_atp = ref false;
 val hook_count = ref 0;
-val time_limit = ref 60;
+val time_limit = ref 30;
 
 val prover = ref "E";   (* use E as the default prover *)
 val custom_spass =   (*specialized options for SPASS*)