Voice/video message unread flag is the same that mention unread flag.
If we mark such mentions as read together with all others we mark
media as watched/listened instantly when they appear on the screen.
So now we mark as read only simple mentions, without "unread" media.
Sum of percent values should never exceed 100%. If any two answers
received same amount of votes, they should show same percent values.
This way sum could be less than 100% (three answers, one vote each),
but this looks better than giving extra vote to some random answer.
John Preston