Jane Austen’s momentous 250 th  birthday—spoiler alert: it’s tomorrow!--can be celebrated anywhere, of course, but it must be extra special to celebrate it in a place steeped in authentic Regency history. In other words: Oh, to be in England this week, for events like these:   * Bath: The Jane Austen Festival’s Yuletide Jane Austen Birthday Ball was surely one of the most coveted tickets of the year, and no wonder: The ball was held in the storied Pump Room , a prime gatheri