Users can't ask for ipv6 bridges with the new bridgedb interface
The new BridgeDB interface doesn't allow users to ask for IPv6 bridges. Apparently, the ipv6=true GET parameter trick still works, but we shouldn't rely on users guessing it.
We should think how the "Give me IPv6 bridges" button should be integrated in the current interface.
For example, if we wanted to keep the current KISS interface, maybe we shouldn't add a new button, and instead we should just return IPv6 bridges like they are normal bridges (and expect the latest PTTBB and the user's OS to support IPv6).