Mention Name Search Tweak

Currently, when using `@` to search for a user to reply to them, it'll show the most recent people talking in the channel first before you type anything, and when you start typing in a name it'll populate from the cache.  However, in much larger servers, there can be dozens of folks with incredibly similar names.

My proposal is that when typing in a name, the list it gives you should still be sorted first by who talked in the channel most recently, and then by alphabetical order as normal.  This would help find and respond to people who you may be in a conversation with on a really busy channel without the risk of not being able to find them due to many similar names.