Add Exam.hs

Exam.hs converts a String to Board
Fixed bugs in AI (in function alphaBeta)
Add getBoard function / modified debug print in AI.hs
Add debug print (path of the best plies)
Add new type (CBoard)

CBoard represents a board with 2 Int64's.
implemented init, readCBoard, and show.
Add functions for CBoard

Constant version of Board (two Int64's)
[not build-passing] Modify AI.hs

AI uses two Int64's