In TV sitcoms and even in TV dramas, Peter MacNicol manages to paint more vibrant and oversized characters, with more eccentricity and flat-out fun, than just about anyone, from John Cage on Ally McBeal to Jeff Kane on Veep. Tonight, he guest stars as the mysterious scientist and hermit Doctor Wolcott, who extends an invitation for the boys to come visit his remote cabin. And they go, perhaps a bit too eagerly…