## Issue Addressed
#1494
## Proposed Changes
- Give the TaskExecutor the sender side of a channel that a task can clone to request shutting down
- The receiver side of this channel is in environment and now we block until ctrl+c or an internal shutdown signal is received
- The swarm now informs when it has reached 0 listeners
- The network receives this message and requests the shutdown
## Issue Addressed
There is currently an issue with yamux when connecting to prysm peers. The source of the issue is currently unknown.
This PR removes yamux support to force mplex negotation. We can add back yamux support once we have isolated and corrected the issue.
## Issue Addressed
#1384
Only catch, as currently implemented, when dialing the multiaddr nodes, there is no way to ask the peer manager if they are already connected or dialing
limit simultaneous outgoing connections attempts to a reasonable top as an extra layer of protection
also shift the keep alive logic of the rpc handler to avoid needing to update it by hand. I think In rare cases this could make shutting down a connection a bit faster.
## Issue Addressed
#1483
## Proposed Changes
Upgrades the log to a critical if a listener fails. We are able to listen on many interfaces so a single instance is not critical. We should however gracefully shutdown the client if we have no listeners, although the client can still function solely on outgoing connections.
For now a critical is raised and I leave #1494 for more sophisticated handling of this.
This also updates discv5 to handle errors of binding to a UDP socket such that lighthouse is now able to handle them.
