emit a sound when North is reached

[AnthillSudoku]

Hi, could you please consider adding a sound when North is reached? Since some users may not want it, it should be possible to enable and disable with a button near the actual ones

Speaking about where you can find open source sounds, I found:

https://github.com/akx/Notifications

where "Sharp.ogg" inside the OGG folder seems good enough, a very short sound not too intrusive

v 1.3 from F-Droid

Thanks