Collective.jsonify

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- Nothing changed yet.

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- Fix "AttributeError: get" that occurred with collective.jsonify 1.5 on Plone 2.1,
by using objectValues() to list items contained in a folder.
[rpijlman]

- Add additional_wrappers to hook into export as promised by the documentation.
[pbauer]

- Do not export None in a DateTimeField as the string "None".
[pbauer]

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- Fixing Out of Memory by swapping base64 implementation.
[gogobd]

- Fix acquisition when object in folder has attribute name.
[maartenkling]

- Fallback for TypeError when _get_at_field_value is broken computedfield.
[maartenkling]

- Add runhook support.
[gotcha]

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- Try Subject and Contributors when subject and contributors give nothing.
[maurits]

- Check if value exists on file like fields
[agitator]

- Export creation_date and modification_date for all objects, not only _is_cmf_only_obj.
For dexterity these values are not present in a schemata, so they are not included as part
of the normal schemata based dexterity export.
[sunew]

- Use self.decode method to get stringified field value when wrapping content
for export.
[instification]

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- Export plone.app.redirector redirects, if available.
Comply with default expectations of redirector section in plone.app.transmogrifier.
[hvelarde]

- Do not export FormGen and Redirection tools.
[hvelarde]

- Show translations from LinguaPlone if canonical is available.
[agitator]

- Fixed value for unknown fields. The value was never calculated
fresh for these fields, so you got the value of the previous field.
Or you probably got a NameError if this was the first field.
[maurits]

- Fix manifest
- Added `CHANGES.rst merge=union` to `.gitattributes`
[ale-rt]

- Added the history to JSON export.
[rristow]

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- Do not require simplejson if we already have the native json module
[ale-rt]

- When doing an export with ``export_content`` and having constraints to skip
items, still allow to walk into subitems of the skipped ones - except for
skipped paths, where the whole path is skipped.
[thet]