Careful rethink of command options, distribution options, distribution

Careful rethink of command options, distribution options, distribution
  attributes, etc.  Biggest change was to the Distribution constructor
  -- it now looks for an 'options' attribute, which contains values
  (options) that are explicitly farmed out to the commands.  Also,
  certain options supplied to Distribution (ie. in the 'setup()' call in
  setup.py) are now "command option aliases", meaning they are dropped
  right into a certain command rather than being distribution options.
  This is handled by a new Distribution class attribute,
  'alias_options'.
Various comment changes to reflect the new way-of-thinking.
Added 'get_command_name()' method to Command -- was assuming its
  existence all along as 'command_name()', so changed the code that
  needs it to call 'get_command_name()'.