I believe this now implements all the checks listed in BOLT-02 for
update_add_htlc, however, the BOLT is sometimes ambiguous,
and actually the checks listed there IMO are insufficient.
There are still some TODOs, in part because of the above.
we were looking at inconsistent ctns
and we were looking at the wrong subject's ctx
all the FIXMEs and TODOs here will still warrant some attention.
(note that test_DesyncHTLCs was passing incorrectly:
the "assertRaises" was catching a different exception)
1. In lnhtlc, sent_in_ctn and failed_in_ctn need to look at the
remote ctx, and they need to be called when we receive a revocation,
not when we send one.
2. In lnchannel, we use 3 lnworker callbacks:
- payment sent/payment failed (called when we receive a revocation)
- payment received (called when we send a revocation)
3. Make revoke_current_commitment return a single value.
The second value was only used in tests, there is no need
to bloat the code with that
- persisted states are saved
- state transitions are checked
- transient states are stored in channel.peer_state
- new channel states: 'PREOPENING', 'FUNDED' and 'REDEEMED'
- upgrade storage to version 21
The few other cases that used SimpleConfig.get_instance() now
either get passed a config instance, or they try to get a reference
to something else that has a reference to a config.
(see lnsweep, qt/qrcodewidget, qt/qrtextedit)
"current" used to be "oldest_unrevoked"; and pending was "oldest_unrevoked + 1"
but this was very confusing...
so now we have "oldest_unrevoked", "latest", and "next"
where "next" is "latest + 1"
"oldest_unrevoked" and "latest" are either the same or are offset by 1
(but caller should know which one they need)
rm "got_sig_for_next" - it was a redundant sanity check, that really
just complicated things
rm "local_commitment", "remote_commitment", "set_local_commitment",
"set_remote_commitment" - just use "get_latest_commitment" instead
in the old code,
`self.hm.received_in_ctn(self.config[REMOTE].ctn + 1)`
did not really make sense as "received_in_ctn" compares the argument against the LOCAL ctn