Add M17 network status to Remote command "status" output.

YSFNetwork: fix ::IsConnected(), it should not take m_enabled in account.

M17Network.h

@@ -46,6 +46,8 @@ public:
 
 	void clock(unsigned int ms);
 
+	bool isConnected() const;
+
 private:
 	CUDPSocket       m_socket;
 	sockaddr_storage m_addr;