July 15, 1958 was a tragic day for John Lennon.    John was making tentative inroads into becoming serious about music, he had started a partnership with Paul McCartney, and suddenly his estranged mother, Julia was killed by off-duty police Eric Clague.      This week, we look at what came before that day, and the years-long custody tug-of-war between sisters Julia and Mimi, and occasionally father "Alf."