MELLETTE - As much as milestones are credited to and celebrated by individual athletes, they don’t exist in a vacuum state. That is, to get 1,000 kills, a hitter needs (at least) one good setter. And to get 2,000 assists, a setter needs (at least) a few good hitters. So when Northwestern seniors Ella Haven and Brooklinn Halvorson each reached those specific plateaus earlier this season, they were both quick to point their fingers at each other. “We grew up playing together ever since 3rd grade,” Haven said. “We’ve been playing together for so long. All that time together on the court has really helped us.” Haven, a 5-foot-9 outside hitter reached the 1,000 kill mark at nearly the same time as Halvorson, the Wildcats’ 5-foot-6 setter, notched her 2,000th assist. It was about as close to perfect as the two could have dreamed. “(It was) so amazing,” said Halvorson, admitting that the two had a countdown going as to how many each of them needed. “I kno