sql.py: run_query(): Factored exception parsing out into new parse_exception()

sql.py: Added EncodingException and parse it in run_query()

sql.py: Removed no longer used NameException

csvs.py: Filter: Added empty close() method to support using it as a stream (such as with streams.ProgressInputStream)

sql_io.py: append_csv(): Don't disable COPY FROM for TSVs, which are now supported using csvs.InputRewriter

sql_io.py: append_csv(): COPY FROM: Wrap provided stream in standardizing stream to fix ragged rows (with unequal # columns) and nonstandard CSV dialects (such as TSV with \-escaped newlines)

csvs.py: Added InputRewriter, which wraps a reader, writing each row back to CSV

csvs.py: Added ColCtFilter, which gives all rows the same # columns

sql_io.py: row_num_col_def: Changed type to integer so the row_num can be populated directly by the insert process

sql_io.py: Added row_num_col_def for use by import_csv(). The row_num column will be necessary again because PostgreSQL unfortunately does not return rows in inserted order (or any stable order: "If sorting is not chosen, the rows will be returned in an unspecified order [which] must not be relied on" <http://www.postgresql.org/docs/8.3/static/queries-order.html&gt;), so an explicit ORDER BY is always needed to ensure staging table rows are retrievable in the order they were inserted.