get persisting of receptors and receptor instance data working

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currently we have some commented out code from our original attempt to serialize receptors, plus we have mtree serialization. This now needs to be moved to or utilized by the data engine code together with the instances code

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We are renaming the data engine the "accumulator" because it's a bit funny (a pun on accumulator registers in CPUs), but it also hints at it's greater function as the persistence engine and acting as the "body"

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This is partially working, but to really get it going requires the context of a boot-up/shudown cycle to confirm that what ran, get's properly restarted. see #22

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as of a491ff0 basic bootup-shutdown sequence working! some receptor state data still not serialized, i.e. vmhost active-receptor list, and all receptor process queue data.