[Bitcoin-development] Squashing redundant tx data in blocks on the wire

[Kaz Wesley]

I've updated the gist, and added an additional proposal that I think
meshes well:
https://gist.github.com/kazcw/43c97d3924326beca87d#ultra-fast-block-validation

sparseblocks + UFBV would tighten the new-block process to this (when
txes have been received in advance):
- receive block (~2kB for 1000 tx)
- check whether block contains txes known to belong to conflict-sets,
and if so whether more than one tx from a single conflict-set has been
included (a few operations on very small sets)
- relay block (~2kB)

The benefits of these changes only occur when the transactions have
been seen in advance, but incentivizing ahead-of-block transaction
propogation is a plus, as Jeff mentioned; working on a block without
first ensuring peers have its transactions would be very expensive
from a miner's point of view.