Separate "mention" and "reply mention" permissions.

Currently, you can either completely enable or disable mentions, which in turn disable mentions cast from replies. However, replies and tagging someone are used in completely different contexts. Replies organize the conversation, but in larger servers, people forget to disable "@" in their reply and end up spamming moderators even when they don't mean to. Give us an option to disable @'s from replies so people can still mention someone when there's important news but not spam their mentions in casual convo.