Increase nf_conntimeout_clients to 5 hours

Maybe we should experiment with making the client circuit timeout higher.

It defaults to 30 minutes. It's new in 0.3.1.

+#define CIRCTIMEOUT_CLIENTS_DFLT (30*60) // 30 minutes
+#define CIRCTIMEOUT_CLIENTS_MIN 60
+#define CIRCTIMEOUT_CLIENTS_MAX (24*60*60) // 24 hours
+    timeout = networkstatus_get_param(NULL, "nf_conntimeout_clients",
+        CIRCTIMEOUT_CLIENTS_DFLT,
+        CIRCTIMEOUT_CLIENTS_MIN,
+        CIRCTIMEOUT_CLIENTS_MAX);