A manifest part may list "rotations" in degrees: [0] locks it, [0, 180]
locks it at 0 with the half turn allowed (Allow180Equivalent), and
[0, 90, 180, 270] is the automatic quarter-turn default. Any other set,
or "rotations" together with "allowRotation": false, is an error naming
the part. Without it, "allowRotation" behaves as before.
Lets converted external benchmark jobs (Nestbolt's 0/180 garment and
box jobs) keep their own rotation rules instead of being widened to
quarter turns.
aj
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