anmesia of last discovery (trunk only)

While testing something, I noticed that my last remaining discovery
would never be forgotten.  The formula
  count = ((count * percent) + 50) / 100
always yields 0 with count==1 and percent==25 (the value used for mind
flayer attacks).  Not likely to come up in actual play very often....

src/read.c

@@ -526,7 +526,7 @@ forget_objects(percent)
 	randomize(indices, count);
 
 	/* forget first % of randomized indices */
-	count = ((count * percent) + 50) / 100;
+	count = ((count * percent) + rn2(100)) / 100;
 	for (i = 0; i < count; i++)
 	    forget_single_object(indices[i]);
 }