schemas/VegCore/VegCore.ERD.mwb: collection: don't inherit from source, because a collection is a scoping entity, not a dataset. a collection may also be used as a dataset, but need not be for the purposes of scoping a specimen's accession_number.

schemas/VegCore/VegCore.ERD.mwb: specimen: removed redundant stamping_institution and donor_institution, because these are now in orig_collection.institution. (it is assumed that stamping_institution and donor_institution are the same, because the first institution to acquire and store a specimen (the donor) is the one that stamps it with an accession_number.)

schemas/VegCore/VegCore.ERD.mwb: specimen: split collection into orig,current_collection because the collection that scoped the accession_number (the orig_collection) is sometimes different than the collection where the specimen is now held (the current_collection, or specimen_holder_institutions), e.g. when the specimen is donated

schemas/VegCore/VegCore.ERD.mwb: collection: added institution, name to identify and scope the collection

schemas/VegCore/VegCore.ERD.mwb: changed taxon_name fkeys to taxon_concept where appropriate, and renamed the referencing columns to *_taxon_concept to clearly indicate the referenced table. taxon_concept fkeys are appropriate whenever a taxon is defined or associated with an observed entity, in which case the assertion is not just to a taxon name but to a defined taxon concept (albeit sometimes an unofficial taxon concept scoped by the collector or identifier).

schemas/VegCore/VegCore.ERD.mwb: specimen: added code_in_individual column

schemas/VegCore/VegCore.ERD.mwb: specimen: added fkey to individual for the individual the specimen was taken from

schemas/VegCore/VegCore.ERD.mwb: individual/stem_observation: made individual/stem nullable because there is not always enough identifying information (stem tag, etc.) to actually associate an identifiable individual with an observation

schemas/VegCore/VegCore.ERD.mwb: moved code from individual to individual_observation because the code is something applied at observation time, rather than something that can be used to track individuals between observations

schemas/VegCore/VegCore.ERD.mwb: moved collection_event from taxon_occurrence to specimen because only specimens are actually collected, while other taxon_occurrences (e.g. individuals) must be uniquely identified by some means that are shared between re-observations (e.g. the stem tag)