convert cell spec to row,col. Eg. ParseCellSpec("B5") = [2, 5]

def ParseCellSpec (spec):
        """convert cell spec to row,col. Eg. ParseCellSpec("B5") = [2, 5]"""
        m = __specRe.match(spec)
        (column, row) = m.groups()
        return (int(row), ColumnToIndex(column))