Add a row to the table

        Arguments:

        row - row of data, should be a list with as many elements as the table
        has fields

def add_row(self, row):

        """Add a row to the table

        Arguments:

        row - row of data, should be a list with as many elements as the table
        has fields"""

        if self._field_names and len(row) != len(self._field_names):
            raise Exception("Row has incorrect number of values, (actual) %d!=%d (expected)" %(len(row),len(self._field_names)))
        if not self._field_names:
            self.field_names = [("Field %d" % (n+1)) for n in range(0,len(row))]
        self._rows.append(list(row))