Set prevalence for default intro #48
Description
It's already pissing to ser multiple default intros. This could be enhanced by allowing to set prevalence for it to make cool easter-egg intros that only play once in a while. For example I'd use it to usually play my default 3 second intro but have a chance for a long one minute intro to play (while fun, that long would get tiring after a while if played every singles time).
You can already kinda do this by setting a long time-frame for the intros, but this would be cleaner.