Current Blockers

To continue moving forward with this effort, there are a few things that need to be resolved, and I can't do that alone.

1. Can I go ahead and add various fixed-size integers, 32 bit floats, and cypherlinks to hsdt? @Dominic
2. Can we make timestamps optional, can the devs of the major clients estimate how much of their code would break? @mix, @Matt McKegg
3. Can we drop feed id and sequence number from the metadata? I can work with any of "yes", "no" and "negotiate as part of the rpc", just need a decision. @Dominic

With the first one resolved, I can write down the final hsdt spec and start implementing (currently leaning towards doing it in rust rather than C).

With the second and third one resolved, we can figure out a specific metadata format. That will open up a tiny digression about binary representation of cypherlinks, and a larger one about signing just a hash of the non-meta data instead of the full data itself. But both of these can wait until they've become unblocked.