Alias not usable in GROUP BY

The following query does not work

```
SELECT
PULocationID, DOLocationID, window_start AS day,
pu_zones.Zone as PULocationName,
do_zones.Zone as DOLocationName,
AVG(fare_amount) as avg_amount
INTO avg_fares
FROM TUMBLE(trips, tpep_pickup_datetime, '1 DAY')
INNER JOIN zones pu_zones ON trips.PULocationID = pu_zones.LocationID
INNER JOIN zones do_zones ON trips.DOLocationID = do_zones.LocationID
GROUP BY day, PULocationID, DOLocationID;
```
While this one does work:

```
SELECT
PULocationID, DOLocationID, window_start AS day,
pu_zones.Zone as PULocationName,
do_zones.Zone as DOLocationName,
AVG(fare_amount) as avg_amount
INTO avg_fares
FROM TUMBLE(trips, tpep_pickup_datetime, '1 DAY')
INNER JOIN zones pu_zones ON trips.PULocationID = pu_zones.LocationID
INNER JOIN zones do_zones ON trips.DOLocationID = do_zones.LocationID
GROUP BY window_start, PULocationID, DOLocationID;
```

`GROUP BY` should support using aliases as well as original field names