Disable banning on instances, optionally only for the instance owner

[phlnx]

In case of high activity, a user could be subjected to a temporary ban. This makes sense in an open puzzle but could be a nuisance in a private instance.

My proposal is to allow for a setting to disable such check, either for the puzzle owner or for any and all potential contributors (in case of an unlisted instance, people entering through the direct link).

Ideally the implementation could either be in the form of a setting when creating the instance, or, probably safer, something that can be switched off also at runtime.