Fix: Correctly nest `h-cite`s
As noticed in jvt.me#989, the rendering of Twitter -contexts has been
broken when there are nested h-cites, as the child element does not
have a separate h-cite, meaning a Microformats2 parser (i.e. for
Bridgy) will pick up the child post, too, which leads to me to posting
correctly to my site, but syndication interacts with the wrong content -
which is bad!
Edited by Jamie Tanna