Feature request: Incrementally reveal paragraphs and list items on a slide.

[tmalsburg]

Similar to Beamer's \pause capability.

This feature doesn't necessarily make sense on all slides, so it would perhaps be good to be able to control on a slide-by-slide basis, e.g. through a property in an org drawer. Alternatively, just use the \pause command? This has the benefit that I can export the slides to PDF and get the same behaviour in the PDF as in org-present.