This commit makes the AddNewChannel expect a OpenChannel instead of a
LightningChannel struct. This moves the responsibility for starting the
LightningChannel from the fundingmanager to the peer, and we can defer
the channel restoration until we know that the channel is not already
active.
In this commit, we extend the Peer interface with a new QuitSignal
method. This method is meant to expose a read-only quit channel which
will allow callers to cancel any actions based on the lifetime of the
underlying peer.
This commit moves the generic interface for
Lightning Network peers so that it can be
imported directly into the switch and gossiper.
Eventually, the majority of the peer logic
would be moved into this package for testing
and modularization.
