TAIPEI (Reuters) - Taiwan has invited Pope Francis to visit, its President Tsai Ing-wen said, just weeks after the Vatican reached a milestone deal on the appointment of bishops with China, which claims the self-ruled island as its own. Last months deal gives the Holy See, Taiwans last remaining diplomatic ally in Europe, a long-sought say over such appointments, although both sides call it provisional and sources have said some key issues remain unresolved.