timeutil

char*       isodate_from_time_t             (time_t t);

time_t      time_add_day                    (time_t time,
                                             int days);

time_t      time_add_week                   (time_t time,
                                             int weeks);

int         time_days_in_month              (int year,
                                             int month);

time_t      time_day_begin                  (time_t t);

time_t      time_day_end                    (time_t t);