MainWindow::handleExit(): just call Platform.exit()
MainWindow::handleExit(): just call Platform.exit()

There's no reason to go through the whole event-handling routine.

CS2103AUG2016-T11-C4/main,snehasp13/main,nightism/addressbook-level4,snehasp13/main,CS2103AUG2016-T11-C4/main,nightism/addressbook-level4