remove unnecessary destructor

We should rely on Qt basic pattern of auto-deletion using parentptr.

example/MainWindow.cpp

@@ -82,21 +82,6 @@ MainWindow::MainWindow()
   generateQrCode();
 }
 
-/**
- * Destructor function.
- */
-MainWindow::~MainWindow()
-{
-  delete m_label;
-  delete m_lineEdit;
-  delete m_saveButton;
-  delete m_qrCodeDisplay;
-  delete m_headerLayout;
-  delete m_verticalLayout;
-  delete m_header;
-  delete m_centralWidget;
-}
-
 /**
  * Generates a QR code from text input & saves it as a SVG file.
  */