Performance and testing improvements

[pdil]

Changes

• Added extra unit tests to get code coverage close to 100%.
• Added Board performance tests.
• Fixed source code indentation.
• Added ability to print Board and Position.
• Implemented Board using bitboards, see performance improvements below.

Performance Improvements

The Bitboard implementation has resulted in a ~280x improvement† in computation time when simulating a full game (85 ply) played with a Board object, including initialization, at the cost of a ~40% increase in memory usage.

Results Comparison

Based on testBoardPerformance() performance test before and after Bitboard implementation.

Metric	Before	After	% Change
CPU Time (s)	5.299	0.019	🟢 99.6% ↘
CPU Cycles (kC)	13177592.595	46831.659	🟢 99.6% ↘
CPU Instructions (kI)	63112699.927	224032.835	🟢 99.6% ↘
Peak Memory (kB)	11002.291	15373.645	🔴 39.7% ↗

Xcode Output

Before	After

† Tested on M1 Pro 8-core CPU (2021 14" Macbook Pro)