channeldb: expand the CommitDiff struct with the addition of LogUpdate
channeldb: expand the CommitDiff struct with the addition of LogUpdate

In this commit we finalized the structure of the CommitDiff struct by
adding a set of LogUpdates, and also a valid CommitSig message.

The LogUpdate struct houses a messages that were transmitted and
locked-in with the new commitment state. We include the LogIndex along
with the wire messages itself in order to be able to properly
reconstruct the update log upon restart.

The CommitSig message included should be transmitted after the set of
LogUpdates, and fully covers the new commitment state and any new (or
already present) HTLC’s that were included as part of the state.

aakselrod/lnd,LightningNetwork/lnd,LightningNetwork/lnd,aakselrod/lnd