Feature request: allow static citation_download link

[vegardinho]

As of now (to my knowledge) formatCitationLink is not triggered unless a link is found by css expression. For some websites, export url is not encoded anywhere in html, so that it must be hardcoded. I've currently gotten around this by matching a dummy-element with url, in order to trigger formatCitationLink, but this is hardly optimal.

An easier means of solving this would be greatly appreciated!