private void appendColumnRange(ColumnRange colRange) {
        if (last == null) {
            first = colRange;
            last = colRange;
        } else {
            last.setNext(colRange);
            last = colRange;
        }
    }
Appends a column range to the linked list of column ranges.

@param colRange the range to append
src/nu/validator/checker/table/Table.java