feed: handle send and receive in class, and convert gui and testfeedlistener to use it
pnl: add settlement for games that end without a proper settlement (just settle to most recent mark)
feed: start adding listener setup
testfeedlistener: code for both threading and non-threading modes
book: rename FeedBook -> Book
gateway: bring in client functionality, and initial sketch of Listener setup (not tested yet)
gateway: clean up exchange order messages
gateway: fix listeners bug and use in test.py
gateway: clean up messages a little more to be consistent with exchange and chess messages
chessgame: add chess message and chess game playback messages
strat: start using listener and message classes, now that they're more fleshed out