So far the script "write_graphs.pl" was assuming that table names were unique even across schemas. This was correct until the EAA had to be taken into account. There are  now two tables "art_type", one in the schema "cover_art_archive" and the other in the schema "event_art_archive". While it  is possible to manually edit the generated DOT graphs to work around this limitation, this case should be handled automatically.

It requires to prefix table names (or "tables" object) with their schema in the JSON source format, and to make the script distinguish between node name and table name.