csvs.py: Added RowNumFilter, which adds a row # column at the beginning of each row

streams.py: LineCountStream, LineCountInputStream: Fixed bug where line_num was 1 too high because it started at 1 and was incremented before each line is returned. It now properly starts at 1, but the initial line_num value is 0 to increment to 1 upon encountering the first line. This off-by-one behavior may have been needed for code that associates an error message with a line #, but such code should add 1 to the line_num to get the line # of the error if the error prevents the next line from being read by the LineCount*Stream.

sql_io.py: import_csv(): Take a reader and header rather than a stream to allow callers to pass in a wrapped CSV reader for filtering, etc.

sql_io.py: append_csv(): Take a reader and header rather than a stream_info and stream to allow callers to use the simpler csvs.reader_and_header() function. This also allows callers to pass in a wrapped CSV reader for filtering, etc.

csv2db, tnrs_db: Removed ProgressInputStream wrapper around input stream, which is no longer needed (and causes overlapping output) now that sql_io.append_csv() prints # rows read

sql_io.py: append_csv(): Wrap input stream in a ProgressInputStream that reports rows (rather than lines) read

csvs.py: InputRewriter: Use new StreamFilter to translate StopIteration EOF to ''

csvs.py: Added StreamFilter

csvs.py: InputRewriter: Also support stream inputs which report EOF as '' instead of StopIteration

sql_io.py: append_csv(): Removed no longer used INSERT mode, since all callers now use the default COPY FROM