Read model types from M_c in summarize_table, summarize continuous vars
Using describe() on all columns now, added function to calculate most frequent values of each column
Added tests for summarize
Not calculating row_id summary stats, dynamic output of index labels in get_column_freqs
Cleaned up conversion from DataFrame back to list of lists, handled columns with more than 5 unique values
Added empirical probabilities of most frequent values, added row_index to output table
Drop unnecessary rows from summary and allow duplicate column names in output