Finding Neverland flies. Occasionally it even soars. The miracle is that the darned thing not only got off the ground, but that this musical prequel to the Peter Pan story arrives on Broadway much improved after a storied, bumpy tour of the hinterlands, with its intermittent charms intact, many of its missteps gone or at least minimized, and a ready appeal to family audiences that could insure a hit if only producer Harvey Weinstein honored his promise to keep ticket…