(WIP) adding players
Refactoring player calls to use ticlj.model.player
Refactoring set-mark-at-index into two functions.
Adding a few more tests to ticlj.model.player
Refactoring to use  rather than explicit empty string
Making game require and import work without use
Initial test for AI
Renaming AI -> UnbeatableAI
Adds an function to get empty indices.
Extracting commong game boards into the spec-helper
Functionality for calculating ai score.
get-empty-indices returns a vector now
Add player choosing.
[not working] starts adding UnbeatableAI.
Fixing UnbeatableAI using simple Minimax.
Making tests less brittle, for real.
Extracting AI and Human players.
Fixing ticlj.game spec
Removing alpha-beta function
Adding alpha-beta pruning