[FR] Use `--wrap=preserve` by default

[eliocamp]

Recent pandoc versions automatically wrap long lines and this has caused some issues in some formats(bookdown, distill, rticles).

It might be desirable to add --wrap=preserve by default in rmarkdown itself so that downstream formats don't need to fix this issue each time.

[cderv]

😅 thanks for opening an issue about my comment in other thread. Yes we probably did not fix that in the right place and we should probably add in html_document_base()