Convert each cell into a tuple suitable for consumption by build_table.

def augment_cells_no_span(self, rows, source):
        """Convert each cell into a tuple suitable for consumption by build_table.
        """
        # TODO: Hardwired str transform.
        # 4-tuple: morerows, morecols, offset, cellblock
        # - morerows: The number of additional rows this cells spans
        # - morecols: The number of additional columns this cell spans
        # - offset: Offset from the line-number at the start of the table
        # - cellblock: The contents of the cell
        return [
            [(0, 0, 0, StringList(str(cell).splitlines(), source=source)) for cell in row]
            for row in rows
        ]