Allow people to edit their own poll

Unfortunately flarum perms don't allow it. We can only allow people to modify all polls which would be bad.

@anthony#2272 nope. I only have one under moderate for change polls. Which would suggest it allows changing for everyone.

I'll check again tomorrow in case I've missed it but I did look earlier to try to do this...

The "Allow users to edit their own polls" permission does in fact exist, but it does not work exactly the same as on ProBoards. On ProBoards, editing your poll would reset the votes. While this was annoying, it importantly prevented users from simply switching the options around to make it seem like the option they wanted won once there were enough votes.

For the time being I'm going to decline this, pending the implementation of a new forum suite this year which I hope will be able to better handle polling.