[Rd] NEWS.md support on CRAN

[Jeroen Ooms]

On Tue, Jun 2, 2015 at 8:42 PM, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
> Several of us have been talking about this, and have more or less decided against pandoc for the within-R version.  It is too hard to build, or to include with R, on weird platforms. Something like commonmark is more likely. We'd also like to separate the parse and render steps.

The commonmark::markdown_xml function gives the parse tree in xml
format. From there we could use something like xpath to query the
content for individual news items and such. I think this is a more
practical way of exposing the syntax tree than deeply nested lists or
an external pointer to the internal C handle.