Collective.dms.mailcontent

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- When listing attachments, do not include filename if it's the same than title.
[sgeulette]
- Marked signed attachment
[sgeulette]

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- Made separate `add_content` method to be overrided.
[sgeulette]

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- Corrected contact imports after code move.
[sgeulette]
- Corrected and improved EmailAttachmentsVocabulary
[sgeulette]

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- Avoided error in reply_form during masterselect widget call.
[sgeulette]

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- Added in EmailAttachmentsVocabulary related files of linked mails (reply_to)
[sgeulette]
- Improved reply form to initialize reply_to widget with incomingmail reply_to values
(including backrefs). Do not include deeper refs.
[sgeulette]

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- Use interface to ckeck context in validateIndexValueUniqueness
(multiple types can use the same interface).
[sgeulette]
- RelatedDocs field (reply_to) use now object_provides criteria
[sgeulette]
- Replaced portal_type test by schema interface providedBy test
[sgeulette]
- Added IOutgoingEmail and IFieldsetOutgoingEmail schema interfaces to describe
email information
[sgeulette]
- Added external_reference_number index
[sgeulette]