Using `BaseCommand.options_list` makes Django use the legacy optparse
parser, which does not set the verbosity attribute correctly. Now the
verbosity argument is always cast to int. Regression in 8568638 (#19973).
Initial report and patch from blueyed.
This is the result of Christopher Medrela's 2013 Summer of Code project.
Thanks also to Preston Holmes, Tim Graham, Anssi Kääriäinen, Florian
Apolloner, and Alex Gaynor for review notes along the way.
Also: Fixes#8579, fixes#3055, fixes#19844.