inputs/SALVIAS/maps/VegX.stems.csv: Fixed PlotObsID mapping to point to sourceAccessionCode so that it would map to the same place as organisms' PlotObsID and the entries would be merged. This will hopefully also fix a SALVIAS stems import bug where the specimenreplicate join on existing/inserted rows matched multiple rows, in spite of using the specimenreplicate_unique_catalognumber UNIQUE INDEX.