ChainListeners should be independent of each other, but in practice this
is not the case because ChainWatchInterface introduces a dependency
between them. Push ChainWatchInterface down into the ChainListener
implementations where needed. Update ChainListener's block_connected
method to take a slice of the form &[(usize, &Transaction)] where each
transaction is paired with its position within the block.
* Channel::get_counterparty_htlc_minimum_msat() returned
holder_htlc_minimum_msat, which was obviously incorrect.
* ChannelManager::get_channel_update set htlc_minimum_msat to
Channel::get_holder_htlc_minimum_msat(), but the spec explicitly
states we "MUST set htlc_minimum_msat to the minimum HTLC value
(in millisatoshi) that the channel peer will accept." This makes
sense because the reason we're rejecting the HTLC is because our
counterparty's HTLC minimum value is too small for us to send to
them, our own HTLC minimum value plays no role. Further, our
router already expects this - looking at the same directional
channel info as it does fees.
Finally, we add a test in the existing onion router test cases
which fails if either of the above is incorrect (the second issue
discovered in the process of writing the test).
They all have a specific structure, so having them in the mess that
is functional_tests isn't really conducive to readability. More
importantly, functional_tests is so big it slows down compilation,
so even dropping a few hundred lines is a win.
