Add handling of page breaks

[ekothe]

redoc does not currently render page breaks when converting to word such that the \newpage latex command is ignored when creating the rdocx output.

It would be helpful to implement a filter as per (https://stackoverflow.com/a/49415018/9449563) to add page breaks created using \newpage to the .docx output (and ideally to convert page breaks added in word back to \newpage

[noamross]

New pages are right now not supported in markdown or in pandoc's conversion format, but adding richer features such as page breaks is a parallel project. Right now such features live in https://github.com/davidgohel/worded. We're coordinating closely so that redoc will eventually handle all the features in that format.

The most likely will be implemented by making such features R code with something like:

This text will be followed by a break page. `doc_pagebreak()`

[tarleb]

This might be helpful when converting to docx, but the reverse direction would be a problem.

[ekothe]

Ideally the same underlying markdown could be built as PDF (e.g. using papaja) or word (using redoc) by changing the output format in the YAML. It looks like @tarleb's option would allow that but @noamross's doc_pagebreak() probably would not. However, I can understand that coordinating with worded might constrain implementation.

(FWIW I've tested redoc on a papaja paper doing just this and the page breaks and styles are really the only major issues).