Fix simulate behavior when the only queried columns are also given (previously returned no rows)
Merge branch 'master' of github.com:mit-probabilistic-computing-project/BayesDB
Add test to make sure plots get saved with save to'
Corrected construct_pandas_df to work with 0-row data, also added test for that case
Merge branch 'fix-pandas-0row-error' of https://github.com/mit-probabilistic-computing-project/BayesDB into fix-pandas-0row-error