Add handling of bound artifacts. When an artifact is bound to an out its facets will only be shown in that Out. They will be removed in the blackboard pass and marked as incompatible by the AttributeWriter

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