(Still) unwise to run compile untrusted gnuplots.

While it is natural to think of plots of documents, I understand it is not safe to compile plots from untrusted sources, and there is no trivial and obviously correct way of filtering out dangerous plots while allowing normal plots. This limits the usefulness of gnuplot in document editors and wiki's. See e.g. http://lyx.475766.n2.nabble.com/PATCH-Proposal-for-a-new-...