Fix jinja block start/end bug

[georgesittas]

Fixes #340

[tobymao]

we need to do pushdown projections here instead

and keep annotate types outside in case it doesn’t work right

[georgesittas]

Annotate types requires at least qualified columns to work properly, because it needs col.table not to be empty. I don't think it'll crash, since it just skips columns for which this isn't true:

for col in scope.columns:  # line 282 in annotate_types.py
    if not col.table:
        continue
...

However, if optimize does fail for some reason and we end up not having qualified columns, I'm not sure if it's worth running just annotate_types.

[georgesittas]

I added pushdown projections.