[Rd] Requirement for pandoc 1.12.3 in R 3.1.3

[Prof J C Nash (U30A)]

Are other developers finding R 3.1.3 problematic because vignette
building requires pandoc 1.12.3, while Linux Mint 17 / Ubuntu 14.04 have
1.12.2.1? R 3.1.2 seems to work fine.

I'd very much like to avoid having to build as large a Linux package as
pandoc, which has given me issues outside of R (it leaves out words,
sentences or paragraphs when converting Latex to epub in a novel I'm
working on, and does so without warning). Possibly concerns like this
are why R has moved to a later pandoc.

Suggestions welcome.

John Nash