Implement seat_philosophers

Implement seat_philosophers

Thanks to the change of how the program keeps track of time
it is possible to set the "last_eaten" member of philo in advance
(to zero - the start) without slowing the seating.

Thanks to this, no delay is necessary before the program checks whether
philos died of hunger. (It was needed in old branch, because
		philosophers initialized their own time at the start of their
		existance, and the check could happen before the time was set)