Like anyone taking over a new post, James Kennerley, Portland’s new municipal organist, would like to revitalize the position and make listeners as excited about the Kotzschmar organ as he is. And judging by the attendance and response to his debut recital on Wednesday evening – Merrill Auditorium was as full as I’ve seen it for an organ concert, and there were whoops of joy after several pieces – he is off to a strong start. Kennerley, a 33-year-old Englishman with a striking resumé that includes studies at Cambridge University and the Juilliard School, and organist and choirmaster positions in London and New York, is the 11th musician to hold the job since it was established in 1912.