mod_archive: Fix duplicate messages stored Message exchanged between users on the same server would be stored twice. This is because both the message hook and the pre-message hook would store for both users. The solution is to make sure the pre-message hook only store for the 'from' user, and the post message hook only store for the 'to' user.

2c07bcf56a36d6e74dc0f5422e89bd61f4d31239 0.8-diverge