Collective.singing

-------------------

- Added optional keyword argument 'override_vars' to IComposer.render and
MessageAssemble.__call__ methods. This is to facilitate overriding of
composer_vars. For example from the sendnewsletter.html form in
collective.dancing. Send-outs stored in TimedScheduler will now
also include 'override_vars'.
[tmog]

- Removed version pinning of zope.app.catalog to <= 3.6.0. This is
handled through our external extends file now. See
https://svn.plone.org/svn/collective/collective.dancing/buildout-extends/0.8.7.cfg
and http://pypi.python.org/pypi/collective.dancinginstallation
[nouri]

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- Changed eventhandlers for subscriptions indexing to look for
the Subscriptions object in 'channel._subscriptions' first.
This allows for a property decorated 'subscriptions' function
that keeps data in '_subscriptions'.
[tmog]

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- Pinned zope.app.catalog version to pre 3.6.0 to avoid issue in
https://bugs.launchpad.net/singing-dancing/+bug/301082
[tmog]

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- MessageQueues are now collective.singing.queue.CompositeQueue - an
optimized version of zc.queue.CompositeQueue. This offers a _much_
faster __len__ and faster access to last queue element.
Tests are stolen from zc.queue with added length checking everywhere.
This maybe belongs directly in zc.queue, but adding stuff in zc namespace
is not for me. ;-)
[tmog]

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- Part of Czech translation.
[naro]

- Some refactoring in order to allow for more customized subscription forms.
[nouri]

- Added french translation.

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- Add the subscriber languages to subscription metadata at
subscription time. [nouri]