Calling serverError with a clientError status code (4xx) means it will
automatically default to Internal Server Error (500) which is in the
server error status code range (5xx). That is undesirable.
So far we only trust i.ytimg.com for YouTube thumbnails, but you can
configure the Oembed plugin in config.php by setting the plugin's class vars:
addPlugin('Oembed', array('param'=>'value', ...));
Some might think this is a security risk or privacy invasive, but as the Oembed
script is already calling remote sites to get information _about_ linked media,
the way to stop it is to disable the Oembed plugin. However it is not certain
it has been migrated out into a plugin properly yet. But try it if you want to.
No validation has been attempted yet. Lots of changes left. This
is visibly not (very) different from the previous CSS layout. But
some simplifications have been made.
Might cause issues with local changes to themes and CSS. Also maybe
javascript which depends on certain legacy microformats elements.
The move to microformats2 is motivated by the announcement that all
microformats should be migrated to version 2, as of 2014-06-20 at:
http://microformats.org/2014/06/20/microformats-org-turns-9-upgrade-to-microformats2
htmLawed cleans stuff out properly, but there's no very good way right
now to show text/html attachments, since everything gets jumbled up with
our own CSS etc. Best would be an iframe or just a new tab or so.
