use result_t, move raw logging and dumping to Port and avoid permanent open/close on ofstream

src/lib/ebus/test/test_port.cpp

@@ -26,7 +26,7 @@ using namespace std;
 int main ()
 {
 	string dev("/dev/ttyUSB20");
-	Port port(dev, true);
+	Port port(dev, true, false, NULL, false, "", 1);
 
 	port.open();