Add option to show notification or hear sound on script completion

Sometimes I have to run a script on a large dataset. This can take +15 minutes. Therefore, it would be nice to have an option to display a notification or play a sound when the script has finished.

It would be neat if this could be done in [the notification area in Windows](https://msdn.microsoft.com/en-us/library/windows/desktop/ee330740%28v=vs.85%29.aspx).

Here's a mock-up of how the option could look (an option per run is preferable, with a default that you can adjust in settings)