Merge the 'rules' branch.

Merge the 'rules' branch.

Give the first alpha a code name.

This branch mostly gets rid of all the approval oriented handlers in favor of
a chain-of-rules based approach.  This will be much more powerful and
extensible, allowing rule definition by plugin and chain creation via web
page.

When a message is processed by the incoming queue, it gets sent through a
chain of rules.  The starting chain is defined on the mailing list object, and
there is a built-in default starting chain, called 'built-in'.  Each chain is
made up of links, which describe a rule and an action, along with possibly
some other information.  Actions allow processing to take a detour through
another chain, jump to another chain, stop processing, run a function, etc.

The built-in chain essentially implements the original early part of the
handler pipeline.  If a message makes it through the built-in chain, it gets
sent to the prep queue, where the message is decorated and such before sending
out to the list membership.  The 'accept' chain is what moves the message into
the prep queue.

There are also 'hold', 'discard', and 'reject' chains, which do what you would
expect them to.  There are lots of built-in rules, implementing everything
from the old emergency handler to new handlers such as one not allowing empty
subject headers.

IMember grows an is_moderated attribute.

The 'adminapproved' metadata key is renamed 'moderator_approved'.

Fix some bogus uses of noreply_address to no_reply_address.

Stash an 'original_size' attribute on the message after parsing its plain
text.  This can be used later to ensure the original message does not exceed a
specified size without have to flatten the message again.

The KNOWN_SPAMMERS global variable is replaced with HEADER_MATCHES.  The
mailing list's header_filter_rules variable is replaced with header_matches
which has the same semantics as HEADER_MATCHES, but is list-specific.

DEFAULT_MAIL_COMMANDS_MAX_LINES -> EMAIL_COMMANDS_MAX_LINES.

Update smtplistener.py to be much better, to use maildir format instead of
mbox format, to respond to RSET commands by clearing the maildir, and by
silencing annoying asyncore error messages.

Extend the doctest runner so that it will run .txt files in any docs
subdirectory in the code tree.

Add plugable keys 'mailman.mta' and 'mailman.rules'.  The latter may have only
one setting while the former is extensible.

There are lots of doctests which should give all the gory details.

Mailman/Post.py -> Mailman/inject.py and the command line usage of this module
is removed.

SQLALCHEMY_ECHO, which was unused, is removed.

Backport the ability to specify additional footer interpolation variables by
the message metadata 'decoration-data' key.

can_acknowledge() defines whether a message can be responded to by the email
robot.

Simplify the implementation of _reset() based on Storm fixes.  Be able to
handle lists in Storm values.

Do some reorganization.