refs bug #460

swap bflag and eflag (begin and end flag for timer sanity check)
old version: bflag = 1, eflag = -1
that lead to the sort function sorting timers with begin=end wrong:
self.nrep_eventlist.extend([(self.newtimer.begin,self.bflag,-1),(self.newtimer.end,self.eflag,-1)])
resulted in (end, eflag) before (begin, bflag) and in a conflict with zapping timers with end=begin (no end time)