Add limited moderation permissions to users with high carma

[r4zzz4k]

We have some people in community who are active, open and can be relied upon mitigation of destructive behavior in chats. Some usual chat tools like vote-kicking are effective but very easy to abuse, so limiting their usage to trusted members might be a good way to avoid their pitfalls.

If karma system is expected to be opaque, we can even allow specified people to start vote-kick and provide everyone with vote buttons, but count only votes of people with enough carma level.