add columns mode used by pandoc's :::::: and ::: blocks (closes #87)

[eddelbuettel]

See #87 for discussion. Works as tested on the vignette that previously needed it in the header.

[coatless]

Maybe add a documentation note the README vignette and pinp layout call mentioning this is supported?

pinp/vignettes/pinp.Rmd

Lines 55 to 62 in 4fc965b

	# Optional: Force one-column layout, default is two-column
	#one_column: true
	# Optional: Enables lineo mode, but only if one_column mode is also true
	#lineno: true
	# Optional: Enable one-sided layout, default is two-sided
	#one_sided: true

pinp/R/pinp.R

Lines 68 to 71 in 4fc965b

	#' \item{\code{one_column}}{(Optional) Logical value to select
	#' one-column mode, default is false.}
	#' \item{\code{one_sided}}{(Optional) Logical value to select
	#' one-sided format, default is false.}

[eddelbuettel]

Could do but not urgent and can be done later. It's optional anyway at the pandoc level. Just that before the additional it broke 😿 and now it no longer does.

It also very much does not need a YAML option. Hence "maybe not".

[eddelbuettel]

The other issue for 'maybe not' is that the side-by-side view of code .... pretty much needs one-column mode which does not fit into our default vignette (as easily). We could try to prove a point and have two columns side-by-side inside one column but it likely going to be awkward.

Your reminder about documenting options is good though.

[eddelbuettel]

For completeness, I tried it. Outer \begin{widetext} ... \end{widetext} then clashes with the width setting pandoc supports. Switching with \onecolumn and back to \twocolumn works, but forces a pagebreak. So not really a candidate for our default vignette.