Stephen Kessler's fun, funny Paul Williams: Still Alive proves that you can revere and challenge a documentary subject at the same time, and in that sense, the film was a tonic after watching two-plus hours of Pearl Jam blow their loads into Cameron Crowe's waiting mouth. Paul Williams is of course the diminutive singer-songwriter who was a veritable Zelig in the '70s, his facile wit making him a favourite guest of Johnny Carson, his unique look making him a viable character actor, his whorish need for attention making him powerless to turn down any offer to appear on television. (The…