Clean up error messages and conditionals in reestablish handling
When we reestablish there are generally always 4 conditions for
both local and remote commitment transactions:
* we're stale and have possibly lost data
* we're ahead and the peer has lost data
* we're caught up
* we're nearly caught up and need to retransmit one update.
In especially the local commitment case we had a mess of different
comparisons, which is improved here. Further, the error messages
are clarified and include more information.
projects / rust-lightning / commit