Updated events, adding new handler pattern and enforcing required keywords.
Updated tracker, removing all references to external classes.
Rewrote much of how strategy handles trackers, moving most of the responsibility for operations into the strategy class itself.
Rewrote signature of event handler slightly again.
Started adding event handling behavior to client.
Minor refactoring of peer.py
Renamed function debencode->dbecode as per Denis
Renamed function, removed main function.
New event handling for tracker.