schemas/vegbien.sql: aggregateoccurrence: Added UNIQUE INDEX that makes an aggregateoccurrence unique within a taxonoccurrence. When the sourceaccessioncode isn't specified (as for individual organisms data, where this goes in plantobservation and taxonoccurrence), this ensures a 1:1 relationship between aggregateoccurrence and taxonoccurrence.
schemas/vegbien.sql: aggregateoccurrence: Added UNIQUE INDEX that makes an aggregateoccurrence unique within a taxonoccurrence. When the sourceaccessioncode isn't specified (as for individual organisms data, where this goes in plantobservation and taxonoccurrence), this ensures a 1:1 relationship between aggregateoccurrence and taxonoccurrence.