Switch to subgants code that allows for computing end date.

[a-t-0]

The code is given in abandoned private research project 6:

def get_end_date(
    subgantt, start_activity, end_activity, previous_end_date, print_min_duration
):
    duration = get_start_to_end_duration(subgantt, start_activity, end_activity)
    print(f"First duration={duration}")
    # duration = start_activity.duration_days
    duration = int(get_duration(start_activity, print_min_duration))
    print(f"activity duration={duration}")
    # exit()
    # get which days are countable
    countable_days = get_countable_days(subgantt)
    # get start date

    if not previous_end_date is None:
        activity_start_date = previous_end_date - datetime.timedelta(days=2)
    else:
        activity_start_date = get_activity_start_date(subgantt, start_activity)
    #    shift = previous_end_date - activity_start_date
    #    print(f"shift={shift}")
    #    print(f"shift={shift.days}")
    #    shifted_start_day = compute_end_day(
    #        activity_start_date, countable_days, shift.days
    #    )
    #    print(f"shifted_start_day={shifted_start_day}")
    #    print(f"activity_start_date={activity_start_date}")
    #    activity_start_date = shifted_start_day

    # compute end date.
    end_day = compute_end_day(activity_start_date, countable_days, duration)
    print(f"end_day={end_day}")
    return activity_start_date, end_day