Improved receive.go

- Fixed configuration listen-port semantics
- Improved receive.go code for updating listen port
- Updated under load detection, how follows the kernel space implementation
- Fixed trie bug accidentally introduced in last commit
- Added interface name to log (format still subject to change)
- Can now configure the logging level using the LOG_LEVEL variable
- Begin porting netsh.sh tests
- A number of smaller changes

src/helper_test.go

@@ -12,6 +12,7 @@ type DummyTUN struct {
 	name    string
 	mtu     int
 	packets chan []byte
+	events  chan TUNEvent
 }
 
 func (tun *DummyTUN) Name() string {
@@ -27,6 +28,14 @@ func (tun *DummyTUN) Write(d []byte) (int, error) {
 	return len(d), nil
 }
 
+func (tun *DummyTUN) Close() error {
+	return nil
+}
+
+func (tun *DummyTUN) Events() chan TUNEvent {
+	return tun.events
+}
+
 func (tun *DummyTUN) Read(d []byte) (int, error) {
 	t := <-tun.packets
 	copy(d, t)