root Makefile: VegBIEN DB: Schemas: schemas/%/backup: Changed file extension to .backup to match what pgAdmin3 expects

inputs/SALVIAS/maps/VegX.stems.csv: Fixed PlotObsID mapping to point to sourceAccessionCode so that it would map to the same place as organisms' PlotObsID and the entries would be merged. This will hopefully also fix a SALVIAS stems import bug where the specimenreplicate join on existing/inserted rows matched multiple rows, in spite of using the specimenreplicate_unique_catalognumber UNIQUE INDEX.

root Makefile: VegBIEN DB: Schemas: Added schemas/%/backup for backing up an import's schema

pg_dump_vegbien: Added data option for backing up an import's schema

sql_io.py: cast(): Don't output warnings for errors that are stored in the errors table, because this clutters the log output unnecessarily. Warnings are still output when there is no errors table.

schemas/vegbien.sql: party: party_unique UNIQUE INDEX: Moved surname before givenname, middlename to enable the index to be used when just the person's last name is known. (Note that if the organization is not known, and explicit NULL would need to be put in for that field to use the index.)

sql_io.py: put_table(): DuplicateKeyException: Uniquifying input table to avoid internal duplicate keys: Include all join columns (including literal values) in the unique index, not just table columns, to encourage PostgreSQL to use the index in a merge join.

sql.py: distinct_table(): Support literal values as column expressions. Filter out untyped NULLs because the type unknown can't be indexed.

sql.py: add_index(): Support literal values as expressions

sql_gen.py: ensure_not_null(): Support Literal value inputs, which are passed through if not nullable