Implemented application login.

Minor UI improvement.
Fixed memory leaks.

application/main.cpp

@@ -1,5 +1,6 @@
 #include "mainwindow.h"
 #include <QApplication>
+#include <QDesktopWidget>
 
 #include <QStringList>
 
@@ -7,6 +8,7 @@ int main(int argc, char *argv[])
 {
     QApplication a(argc, argv);
     MainWindow w;
+    w.move(QApplication::desktop()->screen()->rect().center() - w.rect().center());
     w.show();
 
     return a.exec();