Replace back-quotes with straight-quotes in normal text

[rstub]

• back-quotes used as single opening quotes by TeX are not necessary since csquotes.sty is used to handle smart quotes
• back-quotes can confuse the markdown parser (c.f. section '2.1 Package Creation')

BTW, the closing quote and the last letter of the phrase are awfully close. It might make sense from a typographic point of view to use \textsl{'...'}. If you are interested, I can add this to this PR.

[eddelbuettel]

Thanks for catching the remaining backquotes. A leftover from latex source I guess. I'll have to think about / look at the quotes together with \textsl. There is a bit of redundancy there. Maybe do away with one of them?

[rstub]

Using either quote or \textsl would make a lot of sense. There are already several places where only \textsl is used. For only quotes, I have found two references to 'Rcpp Attributes' in Rcpp-FAQ.Rmd.

[coatless]

Down with \textsl{}!

In all reality, I think that is the only latex specific code still embedded in the vignettes. If it can be removed by typesetting using quotes, then that's an ideal way to go.

[eddelbuettel]

Could do. I like \textsl{} better than \textit{} which markdown's _ gives us. The only thing i care about is the pdf output, though, and to me slanted looks best.