Add auto playing sound file on batch completion

[pangwolin]

Would be nice to have the option to automatically play a custom sound file once a batch has completed.

Mock-up example:


Please consider it.

[pangwolin]

On second thought, if you don't want to bother including sound libraries (understandably) here is an even better idea:

Add a "run custom command". That way, users can invoke their own scripts through the shell, including playing a sound file with "paplay" on Linux for example.