Add ability to pin posts to a list at the top of a topic
#13331
To make it easier to find specific posts important to a thread’s topic. Both the topic creator and moderators should be able to do this.

I’m not sure what this’ll look like yet but I keep running into specific examples where this would be really useful.
https://flash.moe/signature/signature.php?p=bodyhttps://flash.moe/signature/signature.php?p=album
#13333
phrasepin
https://wart.host/20190201_qaG.png
#13334
since posts themselves don't have titles, the pins Will need a phrase :evil:
https://flash.moe/signature/signature.php?p=bodyhttps://flash.moe/signature/signature.php?p=album