Swiss tennis star Roger Federer has defeated Marin Cilic of Croatia 6-2, 6-7, 6-3, 3-6, 6-1 to win the 2018 Australian Open in Melbourne. It is Federer’s 20th Grand Slam title and after going four years without winning a major, he now has won three of the last five. The second seeded Federer, 36, cruised through…