Added new themes for W and Q markers in Historical Discharge WQ charts. ThemeUtil.parseLineColorField() will now use parseColor() to parse the color string. This enables using hex colors in theme configs.

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