Query editor errors when referencing previous cells

Looks like you're not allowed to use aliases. This code fails

```sql
SELECT
b.myvalue
FROM
{{myquery}} as b
```
Wrapping the cell reference within parentheses doesn't work either:
```sql
SELECT
b.myvalue
FROM
({{myquery}}) b
```
And when you want to reference more than one cell with same columns and need to specify the table name, also fails (circular reference https://github.com/HVF/franchise/blob/master/src/db/generic.js#L98 )

```sql
SELECT
{{myquery1}}.id
{{myquery1}}.myvalue as val1,
{{myquery2}}.myvalue as val2
FROM
{{myquery_1}} ,
{{myquery_2}}
USING (id)
```