Pacific Northwest Ballet launched its 50th Anniversary Season with George Balanchine’s enduring Allegro Brillante, an Alexei Ratmansky world premiere, Wartime Elegy, and founding artistic director Kent Stowell’s Carmina Burana. One of the most memorable pairings of the evening was Angelica Generosa and new principal Jonathan Batista in Allegro Brillante. Daring and showy, both appear committed to…