Set level of verbosity for error/warning/status messages. ‘level’ optional, new
level of verbosity. ‘oldlevel’ is the old level of verbosity. The following
levels are supported: 0 = Shut up. 1 = Print errors, 2 = Print also warnings, 3
= Print also some info, 4 = Print more useful info (default), >5 = Be very
verbose (mostly for debugging the driver itself).