* Get rid of explicit __all__ settings and use the @public decorator.
* Get rid of ^L's
* Use expected_count argument for get_queue_messages()
* Various code modernizations.
* Other minor changes to make flake8 happy.

The URL headers (Archived-At and List-Archives) should not be added.

   `X-Message-ID-Hash` although the latter is still included for backward
   compatibility.  Also be sure that all places which add the header use the
   same algorithm.

   None.  (LP: #1203359)

Fixes: bug #1060951

By using `six` I think I have most of the imports squared away.  There's
probably still uses of `unicode` built-ins that need fixing.

The idea is to first get the test suite running (which it doesn't yet), and
then to fix tests.

There's a bug in lazr.config which requires us to patch it for now.

- Boost test coverage of lifecycle.py to 100%

 - Add explicit dependency on zope.event in setup.py.
 - Use Python 3 compatible syntax for specifying that a class implements an
   interface, i.e. the @implementer class decorator.
 - print_function futures.
 - Whitespace normalization.

some new APIs I suspect.

fails when the lock is stolen out from under it (as from a thread)

   otherwise it rejects the message with a 550 error.  Also, the LMTP server
   adds the `X-Message-ID-Hash` header automatically.  The `inject` cli
   command will also add the `X-Message-ID-Hash` header, but it will craft a
   `Message-ID` header first if one is missing from the injected text.  Also,
   `inject` will always set the correct value for the `original_size`
   attribute on the message object, instead of trusting a possibly incorrect
   value if it's already set.  The individual `IArchiver` implementations no
   longer set the `X-Message-ID-Hash` header.

due to _() interpolation) and a few other problems that did not have
immediately obvious fixes.

* Give IMailingList a .domain attribute which looks up the IDomain for its
  .host_name.  This cleans up a lot of code.
* Add a test for the 'confirm' email command.
* Suppress blank lines in email command responses.
* Make the IDomainCollection a utility.

Add an IDomainManager and a global domain manager which can be gotten by
adapting the global config object.

Add an IDomainCollection interface for exposing the domain manager onto the
API.

correctly regardless of how it's used.

* Turn on absolute_import and unicode_literals everywhere, and deal with the
  aftermath.
* Use 'except X as Y' everywhere.
* Make the module prologues much more consistent.
* Use '{}'.format() consistently, except for logger interface.
* Because of the problems with calling ** args with unicode keywords, hide
  calls to Template.substitute() behind an API.

  convenient testing, if -C is not given, then the environment variable
  MAILMAN_CONFIG_FILE is consulted.

- Mailing lists no longer have a .web_page_url attribute; this is taken
  from the mailing list's domain's base_url attribute.

- Incoming MTA selection is now taken from the config file instead of
  plugins.  An MTA for Postfix+LMTP is added.  bin/genaliases works again.

- The LMTP server now properly calculates the message's original size.

- If a message has no Message-ID, the stock archivers will return None for
  the permalink now instead of raising an assertion.

- IArchiver no longer has an is_enabled property; this is taken from the
  configuration file now.

- In bin/create_list, fixed a unicode problem when the language is defined in
  the configuration file.

- Fixed bin/dumbdb, bin/list_lists, bin/remove_list, bin/unshunt, and
  bin/mailmanctl

- config.archivers is a property now, not a dictionary that needs
  initialization from plugins.

- IMailTransportAgent interface has been added.

mailman.configuration -> mailman.config.config
mailman.initialize -> mailma.core.initialize
mailman.loginit -> mailman.core.logging (yay future absolute imports!)

Convert all configurations to lazr.config, though some legacy still remains,
and I haven't been able to remove Defaults.py yet.  Added as_boolean() and
as_log_level() helpers for explicit type conversion.  Added a schema.cfg.

necessary.  Finally delete DEFAULT_EMAIL_HOST and DEFAULT_URL_HOST.  Now
add_domain() must be called in the confirmation file for every domain.

add_domain() itself is now pretty much just a proxy for the Domain
constructor.

Add stop() as an alias for pdb.set_trace() to the documentation doctest globs.