Add supervisor node creation

src/Pipe.h

@@ -66,4 +66,34 @@ private:
 	int status_flags[2];
 };
 
+class PipePair {
+public:
+
+	PipePair(int flags, int status_flags, int* fds = nullptr);
+
+	Pipe& In()
+		{ return pipes[swapped]; }
+
+	Pipe& Out()
+		{ return pipes[!swapped]; }
+
+	const Pipe& In() const
+		{ return pipes[swapped]; }
+
+	const Pipe& Out() const
+		{ return pipes[!swapped]; }
+
+	int InFD() const
+		{ return In().ReadFD(); }
+
+	int OutFD() const
+		{ return Out().WriteFD(); }
+
+	void Swap()
+		{ swapped = ! swapped; }
+
+	Pipe pipes[2];
+	bool swapped = false;
+};
+
 } // namespace bro