How to catch malicios memory manipulation of ND-section: add check before *and* after program

[Sword-Smith]

As mentioned in #173 I've had some concern whether size indicators can be abused maliciously. The VerifyNdSiIntegrity goes a long way to addressing that concern.

A further idea could be to run that snippet both before and after the consensus program. That way it will be very difficult to mutate the ND-part of memory, as that would have to be done in a way that still preserves the size-indicator integrity.

With these two checks, and some more eyeballs on the final product, I feel confident that we can, at least with respect to the assembler code, produce consensus programs that are sound.