It’s encouraging, in these days when emerging artists can so easily find themselves pushed and over-hyped into an early burnout, to find violinist Jennifer Pike taking the slow and careful route to stardom. Only now, a week after her 16th birthday, has she felt ready to face the toughest and most discriminating audience of all, that of London’s Wigmore Hall. But it was worth the wait. Pike’s growing maturity as an artist was immediately apparent.