Sort partslists. Ship .xy file to seeed. Add keithp muffins format.

Sort partslists. Ship .xy file to seeed. Add keithp muffins format.

Sorting partslists puts them in a consistent order.
Seeed needs the placement file to load parts on boards.
Keithp prefers a different content for the muffin labels.

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