schemas/vegbien.sql: taxonpath: Made taxonomicnamewithauthor optional again and include all columns in the taxonpath_unique_within_datasource_by_name unique index so that the original name components can be stored in a separate taxonpath from the taxonpath with the concatenated taxonomic name. (The datasource's taxonpath would not always contain an entry for taxonomicnamewithauthor, so the other columns also need to be used in the unique index.)