(PECL trader >= 0.2.0)
trader_cdldarkcloudcover — Dark Cloud Cover
openOpening price, array of real values.
highHigh price, array of real values.
lowLow price, array of real values.
closeClosing price, array of real values.
penetrationPercentage of penetration of a candle within another candle.
Returns an array with calculated data or false on failure.