Translator role: add (re)-import feature in the translator role

One of the most convenient and fastest way to translate large amount of text is to export in XML format the content (in all lang) and be able to reimport it (in the lang authorized for the translator only).

Currently there is the export feature available for translators but this is not really useful as the import (or reimport/update) feature is not present.

Possible to add this feature

• only reimporting the content in the lang of the translator
• only on existing content (update mode - no creation - excepted if the translator has also the permission to create new objects)