Checks if the guess is valide or makes no sense in context
of previous guesses and results.
A guess is good (feasible) if, compared to each row, it scores the same
result as the compared row did to the secret code.
In other words:
A code c is eligible or feasible if it results in the same values for
Xk and Yk for all guesses k that have been played up till that stage,
if c was the secret code.
X is the number of exact matches. Y is the number of guesses which are
the right color but in the wrong position.
row - The guess to be checked.
ci - The control interface of a game which you want
to use to check if a guess is feasible.