#382 Allow if-then statements in export filter

[Anonymous]

I would really appreciate the possibility of having more advanced conditional exports in the export filter. What I want to be able to do is to prioritise exports, e.g. if a weblink exists and no DOI, export the weblink (with extra text), if a DOI exists, export the DOI but no weblink. If neither exists, ignore. I don't think that's possible at the moment, unless my logic skills have abandoned me. Cheers.