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

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

M17Network.cpp

@@ -194,6 +194,11 @@ void CM17Network::enable(bool enabled)
 	m_enabled = enabled;
 }
 
+bool CM17Network::isConnected() const
+{
+	return (m_addrLen != 0);
+}
+
 void CM17Network::sendPing()
 {
 	unsigned char buffer[5U];