-0 should round trip through pass-style but remain equiv to 0 at patterns level

[erights]

See ocapn/ocapn#58 (comment)

[erights]

Lexicographic order imposes a surprising constraint:

compareRank(-0, 0) === 0;
compareRank([0, 1], [0, 2]) < 0;
compareRank([0, 1], [-0, 2]) < 0;

Therefore

encodePassable([0, 1]).body < encodePassable([-0, 2]).body

Therefore, in a compositional encoding

encodePassable(0).body === encodePassable(-0).body

Therefore, the distinction between -0 and 0 must be outside the body, just as the encoding of the details of remotables, promises, and errors must be outside the body, in order to not break lexicographic order in the same way. See encodeThing currently at

endo/packages/marshal/test/test-encodePassable.js

Lines 43 to 47 in 19180f6

	const encodeThing = (prefix, r) => {
	buffers[prefix].push(r);
	// With this encoding, all things with the same prefix have the same rank
	return prefix;
	};