VegBIEN mappings: Wrapped dates in _date() and _dateRangeStart()/_dateRangeEnd(), to assist in importing date and date range values that PostgreSQL cannot parse. This will increase the import time, but hopefully also decrease the # of invalid values in the errors tables. (These functions can later be optimized to reduce the impact on import time.)

sql_io.py: put_table(): is_literals: is_function: Fixed bug where function call needed to be recreated in each iteration of the main loop, because the arguments to the function, which are based on mapping, may change as the result of error handling replacing invalid values with NULL

sql_io.py: put_table(): is_literals: Fixed bug where sql.select() that calls the function needed to be run recoverably, to auto-rollback errors. Made sql.select() cacheable because SQL functions are immutable, so it should be idempotent.

mappings/DwC2-VegBIEN.specimens.csv: Remapped taxonRemarks to taxondetermination.notes because http://rs.tdwg.org/dwc/terms/#taxonRemarks indicates that these notes are "about the taxon", not the specimen/plant in general

mappings/DwC2-VegBIEN.specimens.csv: Remapped eventDate to new aggregateoccurrence.collectiondate, which is a more accurate place than locationevent.obsstartdate/obsenddate because the date refers to a specific specimen. This also makes eventDate compatible with plots data.

mappings/DwC2-VegBIEN.specimens.csv: Moved sex user-defined mapping to plantobservation because it's a property of the plant rather than the specimen, and so that it can also apply to plots data

mappings: Remapped specimenreplicate.description to new aggregateoccurrence.notes because the notes don't necessarily refer specifically to the specimen, especially for plots data

mappings: Remapped specimenreplicate.description to new aggregateoccurrence.notes because the notes don't necessarily refer specifically to the specimen, especially for plots data

schemas/vegbien.sql: aggregateoccurrence: Added notes, to serve the purpose that specimenreplicate.description previously did. specimenreplicate.description is not appropriate for plots data, and often not appropriate even for specimens data, which uses fieldNotes as a general notes field rather than a description of the specimen.

schemas/vegbien.sql: aggregateoccurrence: Reordered linecover so it's near cover instead of at the end