fix 202 bugs (#418)

* fix peer rpc stop working because of mpsc tunnel close unexpectedly

* fix gui:

1. allow set network prefix for virtual ipv4
2. fix android crash
3. fix subnet proxy cannot be set on android

easytier/src/vpn_portal/wireguard.rs

@@ -81,7 +81,7 @@ impl WireGuardImpl {
         wg_peer_ip_table: WgPeerIpTable,
     ) {
         let info = t.info().unwrap_or_default();
-        let mut mpsc_tunnel = MpscTunnel::new(t);
+        let mut mpsc_tunnel = MpscTunnel::new(t, None);
         let mut stream = mpsc_tunnel.get_stream();
         let mut ip_registered = false;