Sets the column count and list of columns to the inputed column list.
        
        :param      columns | [<str>, ..]

def setColumns( self, columns ):
        """
        Sets the column count and list of columns to the inputed column list.
        
        :param      columns | [<str>, ..]
        """
        self.setColumnCount(len(columns))
        self.setHorizontalHeaderLabels(columns)