Xar handler packager handles objects and attachments in translated documents as if they were in the original document (save, update)

The hard part is knowing where is the cleanest location to fix that: it's not really correct to end up with an translated XWikiDocument contain xobjects and attachments, it's also not very correct for the store to take into account xobject and attachment when saving an XWikiDocument. Problem is that I'm sure we can find code which rely on those behaviors...