Speed up/fix the evaluators.
Make the GameState hashable.
Add a base/hash_map.h header that would 'hide' compiler specific classes.
Switch the caches from tree maps to hash maps.
Store the game type in a GameState instance.
Allow incremental changes to a GameState instead of full board re-encoding.
Fix comparison between signed and unsigned types.
Fix locking issue.
Trying to increase the speed of queue swapping.
Switch to time limited iterative deeepening with hash tables.