Added database class and a logger sample that uses it.
Display traceback for exceptions caught in the bot loop so that it's not as frustrating to debug traders.
The bot now adds the traders to its internal data structures (this makes TraderBase simpler).
TraderBase now expects just a list of pairs it handles.
Added an onExit method to traders to allow them to do thread-specific cleanup; this method is called just before exiting the bot loop.
Added copyright text.