config/VirtualBox_VMs/vegbiendev/README.TXT: added instructions to retrieve the original contents of the backup from the VM

fix: /README.TXT: to back up vegbiendev: also back up /home/aaronmk/bien/ (instead of just symlinking to the local copy), since this can be done space-efficiently with hardlinks. this ensures that the vegbiendev backup will not be modified when the local copy of bien/ is.

lib/csvs.py: JsonReader: factored out row-dict-to-list into new row_dict_to_list_reader so that JSON-specific preprocessing is kept separate from the row format translation

lib/csvs.py: added MultiFilter, which enables applying multiple filters by nesting

lib/tnrs.py: single_tnrs_request(): JSON mode: implemented output of JSON data

lib/tnrs.py: single_tnrs_request(): factored out wrapping in TnrsOutputStream, since this is done for both modes

fix: lib/tnrs.py: JSON mode: TSV export columns: need to translate these to JSON column names before they can be used with the JSON data

lib/csvs.py: added JsonReader, which reads parsed JSON data as row tuples

lib/csvs.py: added row_dict_to_list(), which translates a CSV dict-based row to a list-based one

lib/csvs.py: RowNumFilter: added support for filtering the header row as well