Refactor ComputedDischargeCurveExporter to support WQKms values and WQKms arrays Not only allow CalculationResult objects in ComputedDischargeCurveExporter. Also generate exports from WQKms values and WQKms arrays.

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