Changes made:

Until so far, the "details" and "summary" Handlebars templates referenced
the "text" field of the annotation object, and they automatically
HTML-escaped the content found there.

Since now we are placing HTML unsafe content there (the links),
this had to be changed. So now the templates are using triple-stash
(which means no automatic escaping), and reference the "rendered_text"
field of the annotation object.

This rendered_text is filled by manually escaping the text of the
annotation body, plus making the URLs clickable.