Collective-iconifiedcategory

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- Do no more make the elements using behavior marked with
`IIconifiedCategorization` or `content_category.setter` is not working
anymore.
[gbastien]

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- Adapted tests to use `file_txt` instead `file` as id for default `File`
as `file` is also the name of the field, `portal.file` returns the `File`
instance instead breaking because it does not have a `file` field.
[gbastien]
- Do not break in `utils.validateFileIsPDF` while creating a new element and
no file has been selected.
[gbastien]

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- Added parameter `use_category_uid_as_token=False` to
`CategoryVocabulary.__call__` method to be able to use category/subcategory
as term token instead the calculated content_id (default).
[gbastien]

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- Factorized events triggered when a categorized element attribute is changed
(`to_print`, `confidential`, ...). Now a single `IIconifiedAttrChangedEvent`
event is triggered. Moreover it is optimized to avoid too much process.
[gbastien]
- Removed specific call to `IconifiedAttrChangedEvent('confidential')`
when creating a new categorized element.
[gbastien]
- Added `ICategorize.only_pdf` parameter making it possible to define if the
categorized element is a file, that it can only be PDF. Added also invariant
on `IIconifiedCategorization` checking if file is a PDF when categorized
element has a file field and used content_category has `only_pdf=True`.
[gbastien]

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- Make appearance of column in `CategorizedTabView` coherent with appearance of
detail icon in `categorized-childs-infos` view,
rely in both case on `CategorizedChildInfosView.show`
[gbastien]

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

- Added management of `publishable` attribute like it is the case for `to_print`
or `confidential` attributes. Factorized when possible.
[gbastien]