sql.py: Added constraint_cond()

sql.py: run_query(): ConstraintException: Include table in the constraint name because constraints are scoped by table

sql.py: Added ConstraintException and parse it in run_query()

sql.py: ConstraintException: Also store the constraint's condition, if any

schemas/vegbien.sql: specimenreplicate: specimenreplicate_unique_catalognumber UNIQUE INDEX: Limited to rows where sourceaccessioncode IS NULL, so that it will only be used as an alternate if the datasource does not specify a sourceaccessioncode. This should fix the SpeciesLink bug where input rows with catalognumber_dwc IS NULL match multiple output rows when compared on the specimenreplicate_unique_catalognumber UNIQUE INDEX because they were excluded from the uniquifying by the index filter.

schemas/vegbien.ERD.mwb: Synced with schema

schemas/vegbien.sql: specimenreplicate: Added UNIQUE INDEX on plantobservation_id for direct vouchers in plots data

inputs/import.stats.xls: Updated with stats from latest import

sql.py: Removed no longer used constraint_cols(). index_cols() can always be used for a UNIQUE constraint because a UNIQUE index is automatically created for it.

bin/map: Fixed bug where errors table indexes could not be looked up using index_cols() because their schema was not in the search_path, by explicitly adding the in_schema at the end of the search_path. This is the only reason the in_schema needs to be in the search_path, but it's unavoidable because the "duplicate key value violates unique constraint" error does not included the constraint's schema.