added simple keyboard control

src/main.cpp

@@ -1,5 +1,6 @@
 
 #include <QApplication>
+
 #include "MainWindow.h"
 
 #include <iostream>
@@ -13,5 +14,7 @@ int main(int argc, char *argv[]) {
     MainWindow window;
     window.show();
 
-    return app.exec();
+    int status = app.exec();
+
+    return status;
 }