The client now interprets `rel="noopener"` to mean "check links for
interstice whitelist", and bypasses the interstice if it's not there.
This is is the best approach for [[google links]] to bypass the
interstice, while not whitelisting all of Google because Google
redirects are not generally trustworthy.
This mainly adds support for parenthetical spoilers:
(parenthetical spoiler: these)
They'll be useful for closing any other autoclosing spans in the
future, but currently spoiler is the only one.
This new version supports significantly more client chat formatting
than before, and is more readable.
Also new: the `code` formatting now uses basically the same system as
Markdown, where you can use as many `` ` `` in a row as you want as
your delimiter.
