[Rd] NEWS.md support on CRAN

[Jeroen Ooms]

On Sun, May 24, 2015 at 4:01 AM, Duncan Murdoch
<murdoch.duncan at gmail.com> wrote:
> The "markdown" package does some of what R would need to make use of Sundown, but not all:  we really do need an R object representation of the parse tree, for functions like news() to work with in the short term, and the help system in the longer term.

John MacFarlane's reference implementation does provide the markdown
parsing tree, although by default it is only exposed in xml form. A
quick example:

  devtools::install_github("jeroenooms/commonmark")
  help(commonmark)

>From the xml tree you can easily extract news items using xpath, or we
could hack the libcmark library a bit to get the parse tree as an R
list.