Added a validation SQL query to database backends. Enable it by storing something like "SELECT 1 FROM DUAL" in config under /artifact-database/backend-database/validation-query/text() or /artifact-database/seddb-database/validation-query/text().

SYMBOLSET
SYMBOL
  NAME 'point'
  TYPE ELLIPSE
  POINTS
    1 1
  END
  FILLED TRUE
END
SYMBOL
  NAME "square"
  TYPE VECTOR
  POINTS
    0 0
    0 1
    1 1
    1 0
    0 0
  END
  FILLED TRUE
END
END