bin/map: in_is_xml: doc2rows(): "Root not found in input" error: Changed SystemExit to a warning because this is a normal circumstance in the base case where the input XML file contains no rows

README.TXT: Datasource setup: Documented how to map each table's columns

README.TXT: Datasource setup: Changed "Auto-create the src column spreadsheets" to "Auto-create map spreadsheets" and updated command to bootstrap all maps, including newly-autogeneratable via maps

input.Makefile: Maps building: maps/$(via).%.csv: Auto-create by copying the src map if doesn't exist. Existing maps discovery: Look up via format in src maps' roots if no via map already exists.

src_map: Fixed bug where non-header rows needed to be materialized with empty fields for each column in the header

input.Makefile: Maps building: Via maps cleanup: Match maps/$(via).%.csv with pattern instead of $(viaMaps) var so that a non-existing via map will have the recipe run, too. When auto-creating via maps is later added, this will be required.

inputs/*/maps/src.*.csv: Regenerated using new src_map output format

parallelproc.py: MultiProducerPool: Removed warning if not using parallel processing because this also gets generated when it's explicitly turned off, which is currently the case and clutters up stderr when testing

src_map: Also add columns for the output mappings and comments, so that the src map can be directly copied for use as the via map (DwC.specimens.csv, etc.). The output mapping column name must be provided by the caller, which input.Makefile maps/src.%.csv provides using the new mappings roots.

Added mappings/roots for use in creating src maps