added NAT traversal

core/escape-NAT_test.go

@@ -0,0 +1,16 @@
+package core
+
+import (
+    "fmt"
+    "testing"
+)
+
+func TestEscapeNAT(t *testing.T) {
+    nat, s, err := EscapeNAT("8090")
+    if err != nil {
+        fmt.Println(err)
+        t.Fail()
+    }
+    fmt.Println(nat)
+    fmt.Println(s)
+}