Make tab and csv part import 'the same'.

Make tab and csv part import 'the same'.

.tab files have one line per refdes, .csv files have one line per component.
When importing a .tab file, merge matching components by sorting-in
another refdes. When importing a .csv file, sort the refdes
numerically.

When dumping a .tab file, iterate over the refdes and emit duplicate lines.

Signed-off-by: Keith Packard <keithp@keithp.com>