Allow knitrBootstrap to be used as a vignette engine

[dtenenba]

Currently if a package vignette wants to use knitrBootstrap it has to have a Makefile.
However, if knitrBootstrap registered a vignette engine, then the package author would just have to specify VignetteEngine: knitrBootstrap in DESCRIPTION and %\VignetteEngine{knitrBootstrap::knit_bootstrap} in the vignette. See the discussion on non-Sweave vignettes in Writing R-extensions, and the help for ?tools::vignetteEngine.

[jimhester]

This is true. Pull request #68 should be able to do this using the rmarkdown vignetteEngine already, but it has some other unresolved issues as well. Unfortunately I have been working on other side-projects so knitrBootstrap has been sadly neglected.

Rmarkdown now has ~95% of the features of knitrBootstrap, so I am not sure how much further it is worth taking this project, it seems mostly redundant to me at this point.

[jimhester]

That being said, registering a vignetteEngine shouldn't be too much work, so it can probably be done.

[dtenenba]

Thanks for the feedback. I am dealing with a package that is using knitrBootstrap and having issues, maybe I'll see if the maintainer wants to switch to rmarkdown and/or ask what specific features of knitrBootstrap he wants.