schemas/VegCore/VegCore.ERD.mwb: moved taxon_observation subclasses closer to taxon_observation so that it would be clear they were observation-related rather than occurrence-related (e.g. there is no concept of "repeat-sampling" of an aggregate_observation, because each sampling it is the collector's opinion that the plants correspond to a particular taxon)
schemas/VegCore/VegCore.ERD.mwb: moved taxon_observation subclasses closer to taxon_observation so that it would be clear they were observation-related rather than occurrence-related (e.g. there is no concept of "repeat-sampling" of an aggregate_observation, because each sampling it is the collector's opinion that the plants correspond to a particular taxon)