Begin work on a transposition table
Abstract away the type of the board evaluation
Forgot the return value for get
Abstract away the board hash code type
Implement the transposition table functionality

This is a simple non-concurrent implementation for prototyping
purposes. Testing out the API.
Implement core logic for Zobrist hashing
Add an incremental hash calculation to Board
Show the hash code as a base-16 number
Merge pull request #56 from joichiro/tt

Implemented Zobrist hashing and a transposition table with an API that can use the hash code as a key. Integrated incremental board hashing into the make and undo move routines.