inputs/SALVIAS/verify.sql: Use new :datasource variable instead of literal 'SALVIAS'

input.Makefile: Provide the verify.sql script a :datasource variable set to the datasource name (in quotes)

vegbien.ERD.mwb: Re-marked aggregateoccurrence:plantobservation relationship as 1:1 in the ERD

bin/map: DB, CSV inputs: Use column indexes instead of column names to look up each field (optimization to avoid repeated dict lookups of the same key)

util.py: ListDict: str(): Print each entry on its own line, in the order the keys were provided

NYBG-DwC maps: Filter out MinimumElevation = "."

xml_dom.py: NodeTextEntryIter: Filter out empty entries (instead of producing an entry with an explicit None value, which causes problems with XML funcs that can't handle Nones)

NYBG-DwC maps: Map to input fields with XML func appended whenever possible (DwC1->DwC2 translation is done by DwC-VegBIEN.specimens.csv)

vegbien.sql: Renamed methodtaxonclass.description to methodtaxonclass.taxonclass and changed it to a closed list (enum taxonclass). method.description can still be used for freeform taxonclass inclusions/exclusions.

DwC1-DwC2.specimens.csv: Removed no longer needed /_alt/2 XML func from date mappings (you will only ever map either the full date or the year/month/day)