improve performance of route generation (#914)

this may fix following problem:

1. cpu 100% when large number of nodes in network.
2. high cpu usage when large number of foreign networks.
3. packet loss when new node enters/exits.
4. old routes not cleand and show as an obloleted entry.

easytier/src/peers/mod.rs

@@ -1,3 +1,5 @@
+mod graph_algo;
+
 pub mod peer;
 // pub mod peer_conn;
 pub mod peer_conn;