Remove some dead code
Rewrite position methods to be a class instead.  I left the old free-functions for now, but will be removing them in follow-up commits.  I decided to remove CallHistory.bidding_rounds as it was dead code.
Remove many of the position free functions
Remove position_char
Remove in_partnership_with free function
Fix exception during bidder-fight
Update kbb_baseline
Re-write bidder-fight to talk to kbb over json so we don't have to keep the kbb in the main tree
The KBB is dead. Long live the Z3B
Fold handconstraints.py into knowledge.py
Move PositionKnowledge into the front-end directory since bidder_handler is its only consumer
Remove more mention of the KBB
Remove the kbb-specific make publish
Remove the no-longer used third_party.enum library
Remove more cruft from positionknowledge.py
Add a Strain class with which to eventually replace the strain_ free functions
Remove all the suit_ and strain_ free-functions
Remove incorrect comment
Remove more dead code
Make all identifier methods @propertys