Implement the outpost evaluation

[programarivm]

An outpost can be thought of as a strategic square where a minor piece — a bishop or a knight — is placed in such a favorable way that the opponent definitely wants to trade it for one of their minor pieces, or is even willing to trade it for a major piece. This usually happens when such square is protected by a pawn and cannot be attacked by an opponent's pawn as described in the example below.

Figure 1. w = 2, b = 0

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Thus, a new file named OutpostEvaluation.php should be implemented in a similar way as the following evaluation features:

• CenterEvaluation.php
• MaterialEvaluation.php

With the new feature implemented, we'll be able to take more accurate normalized heuristic pictures; for further information please visit:

• Visualizing Chess Openings Before MLP Classification

See:

• https://github.com/chesslablab/php-chess/issues/53
• https://github.com/chesslablab/php-chess/issues/52
• https://github.com/chesslablab/php-chess/issues/50
• https://github.com/chesslablab/php-chess/issues/49

Keep it up, and happy learning!

[programarivm]

This issue needs to be split into smaller tasks:

• [x] https://github.com/chesslablab/php-chess/issues/195
• [x] https://github.com/chesslablab/php-chess/issues/196
• [x] https://github.com/chesslablab/php-chess/issues/197