Modify how to launch probabilistic events

[alvarocarrera]

Now, only one probabilistic event is launch in a step. Even if 100 events are trying to be launched.

[alvarocarrera]

I think that the reason why this prob events are launched in this way is that the random generator gives the same number if you call it several times in small times. To check this, make a step that print 100 random numbers inside a "for" and check the result.