Trigger bell at random times rather than at a fixed period about mindbell HOT 5 CLOSED

this needs more work -- you cannot schedule several instances of the same 
Intent using AlarmManager.set(), so need to reschedule every time we ring the 
bell...

Thank You very much por this excelent project.
I love this application..but I'd like ring the bell at times o'clock, not 
random (at 9:00, at 10:00, or subtimes, as 9:15, 9:30,...not 9:13 or 9:23..). 
This could be a option in the menu (random, time o'clock hh:00)
(Sorry for my poor english, I'm from Madrid, Spain)

Thank you once more. Best wishes.
Kike

done in r71