Fix #1380

Add No Prefix and Any Prefix filter/sort options.
https://github.com/mybb/mybb/issues/1380
> That is why standards are created on the first place.

But as I said above it doesn't break any standards. Many queries in MyBB have spaces before/after = too and noone is complaining about that.

> You modified something unnecessarily yet the rest of the document works opposite to your preferences

You're right, but if I'm writing/testing a code I always edit it so it matches my style. I did it in other PRs too and noone had problems with that till now.