Added 'force' and 'quiet' (negative alias for 'verbose') to the

  global options table.
Every Command instance now has its own copies of the global options,
  which automatically fallback to the Distribution instance.  Changes:
  - initialize them in constructor
  - added '__getattr__()' to handle the fallback logic
  - changed every 'self.distribution.{verbose,dry_run}' in Command to
    'self.{verbose,dry_run}'.
  - filesystem utility methods ('copy_file()' et al) don't take 'update'
    parameter anymore -- instead we pass 'not force' to the underlying
    function as 'update'
Changed parsing of command line so that global options apply to all
  commands as well -- that's how (eg.) Command.verbose will be initialized.
Simplified 'make_file()' to use 'newer_group()' (from util module).
Deleted some cruft.
Some docstring tweaks.