Fix slave ID generation. Always increment the ID at least once on every call, even if there's no conflict, since we don't require slaves to be added to containers immediately. Gaps are OK, conflicts are not OK. Fixes #5396 (closed)
Also, don't bother with checking for conflicts in V.missingTable, since missing slave IDs are always negative.
Improve the way embedded menial trading works...you no longer have to embed the entire market passage, and the menial trading code owns its own container and can refresh it without a DOM search.