improve mycelium argument

Listings/mycelium_route_constants.rs

@@ -0,0 +1,9 @@
+/// Time between HELLO messages, in seconds
+const HELLO_INTERVAL: u64 = 20;
+/// Max time used in UPDATE packets.
+const UPDATE_INTERVAL: Duration =
+    Duration::from_secs(HELLO_INTERVAL * 3 * 5); // 300 s
+
+/// The amount a metric of a route needs to improve
+/// before we will consider switching to it.
+const SIGNIFICANT_METRIC_IMPROVEMENT: Metric = Metric::new(10);