Products.daterecurringindex

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Breaking changes:

- *add item here*

New features:

- *add item here*

Bug fixes:

- *add item here*

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- Python 3/ Zope 4 compatibility.
[pbauer, jensens]

- Code alignment to Products.ZCatalog 4.
[thet]

- PEP 8.
[thet]

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- Fix the manage template declaration and avoid the deprecation warnings on
Zope startup.
[thet]

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- Licence and contributors updates.
[jensens]

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- Use tuple to store self._unindex (reverse index) values, instead of an
IISet, allowing for proper sorting, intended to fix:
https://github.com/collective/Products.DateRecurringIndex/issues/1
For proper sorting, existing installations may wish to reindex any
indexes installed in their catalog using DateRecurringIndex.
[seanupton]

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- Fixed broken manage template.
[romanofski]

- Added template to browse index contents.
[romanofski]

- Repackaging: Fixing MANIFEST.in and adding missing files.
[thet]