Prevent a user from editing a post to bump to the top of a forum

[aaroncox]

https://chainbb.com/chainbb-support/@revo/possible-avenue-for-abusing-chainbb

There was a fix for this at one point, but the indexer needs to be altered to prevent this. Perhaps by setting a timestamp equal to the created data on first insert, never changing that again, and using that for sorting (since the APIs themselves might be bumping at this point).