Fix subscribing to "real time" transactions.
Fix a pathfinding bug
Pathfinding improvements:
* Make each path request track whether it needs updating.
* Improve new request handling, reverse order for processing requests.
* Break to handle new requests immediately.
* Make mPathFindThread an integer rather than a bool. Allow two threads.
* For old pathfinding, if the ledger is unspecified, use the PathRequest's RippleLineCache.
* Log new pathfinding request latencies.
* Suspend processing requests if server is backed up.
Pathfinding bugfix. Missing lock.
Concurrent SHAMap code
Use shared lock for SHAMap itself and concurrent map for nodes
PathRequests object to own all path requests.
Pathfinding cleanups
Make the extraPath work correctly with old pathfinding.
Handle offers in quality directory but not in ledger
Fix RippleBookType and unit tests
Fix static storage duration issue with some Journal logs
Improved async stop for Resolver

Conflicts:
	src/ripple_app/peers/NameResolver.cpp
Fix Resolver contract check
Disable NameResolver temporarily
Reduce StatsDCollector log verbosity
Refactor IP::Endpoint
Refactor Peer, Peers. Peerfinder work. Remove TESTNET.
Support fixed peers (with DNS) in PeerFinder