request: improve Connect-Four's minimax implementation

[kyranet]

The package uses minimax¹ to determine the best move, however, the implementation is flawed, reporting only three states (OUTCOME_HUMAN_WINS, OUTCOME_MACHINE_WINS, or OUTCOME_DRAW), resulting on very bad moves which result on always playing the leftmost column.

This update would most likely only require a new method that's called inside the remaining == 0 conditions, replacing OUTCOME_DRAW with a call to the new method that evaluates the score heuristically.

Footnotes

1. https://en.wikipedia.org/wiki/Minimax ↩