This currently assumes the event, that is replied to, is already
fetched. If it isn't, it will render an empty reply. In the future we
should fetch replies before rendering them.

fixes compilation issues with last released lmdb++

This also removes an ugly hack, that was needed before.

It is a bit of a hack, but it works...

No idea, why apply visitor doesn't work with temporaries?

Also lays a bit of groundwork for better reply rendering

Thanks to red_sky for the feedback!