beep_darwin: beep without requiring special system events permissions

[stefanb]

$ osascript -e "tell application \"System Events\" to beep" 

raises

if user denies that there is an error:

36:40: execution error: Not authorised to send Apple events to System Events. (-1743)

and there is no beep.

On the other hand, a simpler:

$ osascript -e "beep" 

does not require any extra permissions and it makes mac beep without any prompts.

[gen2brain]

Merged, thanks!