* 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.
* Fix for msvc std::function return types
* Convert macros to constants
* Add Journal to PeerSet and use in InboundLedger
* Break lines and add annotations
* Remove some warnings
* Don't let ledger idle interval get too short
* Fix CBigNum::setuint256
* Fix SqliteStatement::isError
* Remove dead code, fix incorrect comments
* Check for NULL earlier in CKey constructors
* Prevent expire times from underflowing in TaggedCache
* Inbound ledger and SHAMapAddNode cleanup
* Log acquire stats
* Fix progress logic
* Remove ledgers we no longer need to acquire
* Stash stale state data in our fetch pack, it can still be useful
* Stash in fetch pack if acquire terminated while job was pending
* Account for duplicate/invalid nodes in a few cases previously missed
* Dispatch each InboundLedger once (not per data)
* Trigger only the "best" peer
* Don't call tryAdvance on failed acquires