pandoc doesn't have a lot of USE-flags, so I thought the given deps where enough to satisfy all it's features. Turns out, that isn't the case. When trying `pandoc -f something -t {beamer,latex} -o some.pdf some.input`, it complains about 'pdflatex' not being found. So either it should have a USE flag which pulls the needed packages or an einfo notice that for conversion to PDF, further packages are needed.
