streams.py: FilterStream: Forward all reads to readline()

strings.py: Added is_ctrl() and strip_ctrl()

xml_parse.py: parse_next(): On parser error, advance to next XML document since the rest of the current document is corrupted

streams.py: Added consume(). Added documentation labels to each section.

bin/map: For XML inputs, wrap sys.stdin in a LineCountStream and use new xml_parse.docs_iter() on_error() to add input line # to XML parsing exceptions

xml_parse.py: Added on_error() handler to parse_next() (passed through by docs_iter()), so that the caller can add useful info like the input line # to the exception message, and decide not to suppress rather than re-raising the exception

VegX-VegBIEN.organisms.csv: Renamed individualOrganismObservation user-defined field identificationLabel2 to identificationLabel. Distinguish what are now two identificationLabel fields of the same name by tagging each one with [@id=2] or [@id=1]. inputs/SALVIAS-CSV/maps/VegX.organisms.csv: Merge tag1/stem_tag1 and tag2/stem_tag2 using _alt, since they are never set to different values when both are not NULL (although sometimes just one or just the other is not NULL).

VegX-VegBIEN.organisms.csv: Renamed individualOrganismObservation user-defined field tag2 to identificationLabel2 to reflect that it will become a second instance of identificationLabel

VegX-VegBIEN.organisms.csv: Re-mapped individualOrganismObservation user-defined field lineCover to already existing volumeCanopy

VegX-VegBIEN.organisms.csv: Re-mapped individualOrganismObservation user-defined field cover to already existing attribute.coverPercent