Since we now use the short_channel_id to identify the next hop we need
to resolve the channel_id to the pubkey of the next hop. This is done
by calling out to `gossipd` and stuffing the necessary information
into `htlc_end` and recovering it from there once we receive a reply.
Mainly switching from the old include to the new include and adjusting
the actual size of the onion packet. It also moves `channel.c` to use
`struct hop_data`.
It introduces a dummy next hop in `channel.c` that will be replaced in
the next commit.
We use the fourth value (size) to determine the type, unless the fifth
value is suppled. That's silly: allow the fourth value to be a typename,
since that's the only reason we care about the size at all!
Unfortunately there are places in the spec where we use a raw fieldname
without '*1' for a length, so we have to distingish this from the
typename case.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
