SOURCE: The Times DATE: 16 February 1991 Last chance...;Arts Briefing BOB Dylan completes his extended residency at west London's Hammersmith Odeon (081-748 4081) with shows tonight and tomorrow night. Now out of touch with the modern world, the former spokesman of a generation has become an erratic performer whose shows are entirely subject to caprice. With material taken mostly from his Sixties portfolio, and a sparky new backing band of no discernible pedigree struggling to read its boss's unpredictable mind, the results vary from the mundane to the heroic. (c) Times Newspapers Ltd. 1991 --