Ctrl-Q from the main window now quits the application.

Not tested on macOS, does it need to be separately handled?
Not tested on Windows either...

src/MainWindow.cc

@@ -22,6 +22,8 @@
 #include <QNetworkReply>
 #include <QSettings>
 #include <QSystemTrayIcon>
+#include <QShortcut>
+#include <QApplication>
 
 MainWindow *MainWindow::instance_ = nullptr;
 
@@ -84,6 +86,9 @@ MainWindow::MainWindow(QWidget *parent)
                 this,
                 SLOT(showChatPage(QString, QString, QString)));
 
+        QShortcut *quitShortcut = new QShortcut(QKeySequence(Qt::CTRL + Qt::Key_Q), this);
+        connect(quitShortcut, &QShortcut::activated, this, [=]() { QApplication::quit(); });
+
         QSettings settings;
 
         if (hasActiveUser()) {