Feature request: Unnumbered printouts for testing/preview

[noseshimself]

As there is no "preview rendered document" feature yet I tend to create printouts of unfinished documents which are counted. Not only do they get these pesky numbers but I have to erase them after use which is resulting in Kraft telling me "Archivierte Dokumente können nicht gefunden werden. Überprüfen Sie das PDF Ausgabe Verzeichnis."

Two possible solution: "Generate a preview" as additional menu item or having the requested "under construction"/"template"/"final"/"locked" states (and if a document in "locked" state is printed again, stamp it as copy (yet another variable for Weasyprint 8-() and don't give it yet another number.