Watching Damien Chazelle's La La Land in 2016 - a year which, both inside and outside the cinema, has been caked in some of the most feculent matter to spurt from the world's rancid arsehole - is like being slapped in the face with a bright yellow cartoon hand that bursts into stars on impact with your chops, showering you with music and joy and laughter and love and all the things that have