Bug #5479 : work done for 5.14.x merged for 5.13.x

Cf. https://github.com/Silverpeas/Silverpeas-Core/pull/506

Also, taking into account a new detected problem around the copy of a versioned attachment that had several language contents before to be turned into versioned attachment.
The problem was that the result copy of this kind of attachment was keeping only one of the several language contents for its initial version.