Refactor IP::Endpoint
PeerFinder work and refactoring:
* Implement PeerFinder business logic.
* Support fixed peers (including DNS support).
* Add journal support to Peer and Peers.
* Refactor PeerDoor support.
* Tidy up Peers and eliminate connection functionality and timers.
* Refactor Peer interface and add journal support.
* Allow construction of incoming Peer using an existing socket.
* Remove TESTNET support.
* Allow connections from/to cluster peers without consuming slots
* Misc. cleanups.
Resolver Work:
* Don't stall during shutdown
* Properly handle unit test execution
* Handle whitespace when parsing names to resolve
Ignore ports when checking RPC IP filter list
Performance fixes: decongest master lock