schemas/vegbien.sql: 1_to_1 and *_unique_within unique indexes with a `WHERE sourceaccessioncode IS NULL` filter: Added IS NULL filters for other unique keys, so that these fallback indexes would only be used if there was no (or no other) way to uniquely identify their tables. For *_1_to_1 unique indexes, this is the case for specimens data.

schemas/vegbien.sql: 1_to_1 and *_unique_within unique indexes with a `WHERE sourceaccessioncode IS NULL` filter: Added IS NULL filters for other unique keys, so that these fallback indexes would only be used if there was no (or no other) way to uniquely identify their tables. For *_1_to_1 unique indexes, this is the case for specimens data.

schemas/vegbien.sql: stemobservation: Replaced stemobservation_unique_code unique constraint with stemobservation_unique_within_plantobservation unique index that uses COALESCE and WHERE ... IS NOT NULL appropriately, to work with sql_gen's use of COALESCE indexes and (for the renaming) to better reflect what it does

schemas/vegbien.ERD.mwb: Synced with schema

schemas/vegbien.sql: 1_to_1 and *_unique_within unique indexes intended to operate only when sourceaccessioncode is NULL: Changed to use `sourceaccessioncode IS NULL` WHERE condition instead of COALESCE element, since the sourceaccessioncode is not actually needed for the uniquification (it is already globally unique within the datasource if it's not NULL; this just covers the case where it is NULL)

schemas/vegbien.sql: unique_within unique indexes used for 1:1 relationships: Renamed to __1_to_1 to better reflect what they do

schemas/vegbien.sql: unique_within unique indexes used for 1:1 relationships: Renamed to __1_to_1 to better reflect what they do

schemas/vegbien.sql: plantobservation: Corrected plantobservation_aggregateoccurrence_id_1_to_1's name to plantobservation_aggregateoccurrence_1_to_1 because it's 1:1 with aggregateoccurrence, not aggregateoccurrence_id. Made it a unique index for consistency with our general method of expressing unique constraints on potentially nullable columns.

schemas/vegbien.sql: specimenreplicate: Renamed specimenreplicate_unique_plantobservation to specimenreplicate_plantobservation_1_to_1 to better reflect what it does

schemas/vegbien.sql: locationevent unique indexes: Renamed to unique_within to better reflect what they do