Feature: add mode script

tunnel/mode.go

@@ -13,6 +13,7 @@ var (
 	ModeMapping = map[string]TunnelMode{
 		Global.String(): Global,
 		Rule.String():   Rule,
+		Script.String(): Script,
 		Direct.String(): Direct,
 	}
 )
@@ -20,6 +21,7 @@ var (
 const (
 	Global TunnelMode = iota
 	Rule
+	Script
 	Direct
 )
 
@@ -63,6 +65,8 @@ func (m TunnelMode) String() string {
 		return "global"
 	case Rule:
 		return "rule"
+	case Script:
+		return "script"
 	case Direct:
 		return "direct"
 	default: