More adjustments

Fixes issue Feature #5211 http://tracker.modx.com/issues/9362
Fixes issues Bug #9525 http://tracker.modx.com/issues/9525

1. Normalizes participants for thread and impoves index usage for
participants list.
2. Now "Mark all Read" works per section: All unread, since last login
and replies to posts
3. Replies count is not bound to user login time anymore. ^--- #9525

To use new disThreadParticipant when not using package to upgrade, run
new lines from resolve.db.changes.