Photo: Nathaniel S. Butler/NBAE via Getty Images Sometime during the second half of game four of the Eastern Conference Finals between the Knicks and Celtics on Monday night, an entirely unfamiliar thought leapt to the mind of anyone who had watched the entire series up to that point: The Knicks could actually win this thing. That’s a strange thing to say about a team that won the first two games of the series, a team that in fact held a 2-1 series lead at this point. But — now that they’re