Ditched the whole notion of "alias options": this meant dropping the
'alias_options' table and getting rid of some hairy code in the
Distribution constructor.
Resurrected the distribution options that describe the modules present
in the module distribution ('py_modules', 'ext_modules'), and added
a bunch more: 'packages', 'package_dir', 'ext_package', 'include_dirs',
'install_path'.
Updated some comments.
Added 'warn()' method to Command.
'Command.get_command_name()' now stores generated command name in
self.command_name.