* Allow domain blocks to reject media without silencing or suspending
* Fix typo
* Hide 'Reject media' button when superfluous, instead of disabling it
* Properly hide 'reject media' checkbox on page load if needed
This may happen when resubmitting the domain block form after an error.
* Don't ask whether undoing a media-only block should be retroactive
* Rename :media_only block to :noop
* Display :noop block as None in frontend, allow blocks that do nothing
* Remove 'coding' line auto-added by emacs