Fix coding style for various things

src/app/cmdoptions.cpp

@@ -486,7 +486,7 @@ CommandLineParameterError::CommandLineParameterError(const QString &messageForUs
 {
 }
 
-const QString& CommandLineParameterError::messageForUser() const
+const QString &CommandLineParameterError::messageForUser() const
 {
     return m_messageForUser;
 }

src/app/main.cpp

@@ -202,7 +202,7 @@ int main(int argc, char *argv[])
         // this is the default in Qt6
         app->setAttribute(Qt::AA_DisableWindowContextHelpButton);
 #endif
-#endif
+#endif // Q_OS_WIN
 
 #if defined(Q_OS_MAC)
         // Since Apple made difficult for users to set PATH, we set here for convenience.

src/app/upgrade.h

@@ -83,7 +83,7 @@ bool userAcceptsUpgrade()
     msgBox.move(Utils::Misc::screenCenter(&msgBox));
     if (msgBox.exec() == QMessageBox::Ok)
         return true;
-#endif
+#endif // DISABLE_GUI
 
     return false;
 }