This commit refactors `collectResultAsync` such that this method is now
only responsible for collecting results from the switch. The method
`decideNextStep` is expanded to process these results in the same
goroutine where we fetch the payment from db, to make sure the lifecycle
loop always have a consistent view of a given payment.
The routing package implements authentication+validation of channel
announcements, pruning of the channel graph, path finding within the network,
sending outgoing payments into the network and synchronizing new peers to our
channel graph state.
Installation and Updating
$ go get -u github.com/lightningnetwork/lnd/routing
1acf4d7d4d
