add appliction icon

src/main.cpp

@@ -1,14 +1,12 @@
 #include "MainWindow.h"
 #include <QApplication>
 #include <QStyleFactory>
+#include <QIcon>
 
 int main(int argc, char *argv[])
 {
     QApplication app(argc, argv);
     
-    // Set a modern style
-    app.setStyle(QStyleFactory::create("Fusion"));
-    
     MainWindow window;
     window.show();