Fixed missing styles of headings in motion pdf.
Fixed missing styles of headings in motion pdf.

Also some refactoring/clean up of pdf code.

CatoTH/OpenSlides,FinnStutzenstein/OpenSlides,CatoTH/OpenSlides,normanjaeckel/OpenSlides,jwinzer/OpenSlides,normanjaeckel/OpenSlides,FinnStutzenstein/OpenSlides,FinnStutzenstein/OpenSlides,normanjaeckel/OpenSlides,tsiegleauq/OpenSlides,boehlke/OpenSlides,boehlke/OpenSlides,emanuelschuetze/OpenSlides,emanuelschuetze/OpenSlides,OpenSlides/OpenSlides,normanjaeckel/OpenSlides,ostcar/OpenSlides,ostcar/OpenSlides,emanuelschuetze/OpenSlides,OpenSlides/OpenSlides,ostcar/OpenSlides,jwinzer/OpenSlides,tsiegleauq/OpenSlides,jwinzer/OpenSlides,FinnStutzenstein/OpenSlides,jwinzer/OpenSlides,boehlke/OpenSlides,CatoTH/OpenSlides,boehlke/OpenSlides,tsiegleauq/OpenSlides,CatoTH/OpenSlides,jwinzer/OpenSlides,emanuelschuetze/OpenSlides