pre_compute accepts kwargs
Large csv files compute with pandas in chunks
Merge branch 'postgres-doesnt-fail-if-different-credentials' into pandas-chunking
into: Iterator <- DataFrame
csv: reorder columns in _iter, not in pandas_read_csv

This is nice because we retain the TextReader type information
csv: nicer pre_compute on Head and Projection
csv: use lean_projection in chunking case
Merge pull request #863 from mrocklin/pandas-chunking

CSV computation through pandas chunks