Collective.singing

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

- Added ``keep_sent_messages`` flag on channels which, if set to
``False`` (the default), suppresses the behavior which would
otherwise put sent messages into a persistent queue.

If sent messages are dropped (as per this flag), an entry is instead
written to the log to keep a minimal record of events.
[malthe]

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

- Moved z3c widget template registration for radio buttons and checkboxes
from ``browser/configure.zcml`` into ``widgets.zcml`` because every version
of z3c.form after 2.3.3 includes these template registrations and double
registration raises ConfigurationConflictError. [saily]

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

- import zope.app.container.interfaces; this helps for Plone 4
compatibility.
[maurits]

- strange issue with equality of scheduler objects adressed.
This seems to only be an issue in python 2.6.
This should probably be released soon since it fixes a lot
of bugs in the ForPloneFour branch of dancing.
[tmog]

- Norwegian translation. [regebro]

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

- Update Dutch translation.
[maurits]

- Update French translation
[toutpt]

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

- API change! Added boolean "subscribeable" to IChannel.
[tmog]

- Added Brazilian translation
[lucmult]

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

- Optimization for clearing a MessageQueue. We now simple create a fresh
queue instead of pull()'ing all items (pulling is quite expensive with
CompositeQueue).
[tmog]

- Subscription creation date is now used as que when the subscription has
no real cue. I.e. the first time a new subscription is used.
I was amazed to find this was not already the case.
[tmog]

- Triggering a periodic scheduler that has a delta now always updates
trickered_last by a product of that delta. This means the periodic
schedulers now no longer suffer from the time "drift" that resulted
from always saving the precise triggering time to their triggered_last
attribute.
[tmog]

- Added caching of item formatting via plone.memoize.request.
This really(!) speeds up message generation, especially when
sending 'full' items from 'send as newsletter'.
[tmog]