Refactor the grid; simplify some methods and remove unnecessary docs
Don't require clear to return self
Move grid_spec.rb
Refactor the evaluator; simplify some methods and clarify docs
Don't make the evaluator a singleton
Add a missing assertion
Add a test for Evaluator.xos
Move evaluator_spec.rb
Since evaluator is no longer a Singleton we need to fix how it is used by the engine and by the Minimax algorithm
Refactor the Minimax class
Revert Evaluator to a Singleton
Move around some specs and remove unused code from the geometric grid spec
Add missing require statements
Update the README
Update the gemspec's description
Move the engine spec