One more audible alert feature request

[p1839251]

Hey, I'd like to add one more sound effect to SafeEyes exactly when the break starts. 'Play audible alert before breaks' plays it when the 'prepare for a break' bubble appears (this is 30 seconds prior to the break here) and nothing when the actual break starts. I worked around this issue by adding 29 secs long silence to my wave file, but this isn't super reliable as it highly depends on the system load and most of the time they aren't in sync at all. I basically kept your on_pre_break.wav file and just extended it with some silence and one extra sound effect. I think it would be great if there were a 3rd audible alert option.