Update default RGL hook to handle a vector for options$dev
Merge pull request #703 from ajdm/feature/rglmultidev

Update default RGL hook to handle a vector for options$dev
which(grepl(x)) = grep(x), and which(a | b) = unique(c(which(a), which(b)))
report all possible Sweave lines, and always issue a warning message in the console so that the user can see it even after the dialog box is closed
ffmpeg.opts is not used
no more compatibility for opts_knit$get('documentation')
do not ignore .Rproj
I do not remember why knit_code must be emptied before purl()
closes #607: purl() can be done in the process of knit() now
roxygenize
closes #708: no longer overwrite options(tikzMetricsDictionary) unconditionally
make sure foo.R is not removed by default; it is only removed when hook_purl() is called
closes #697: respect the `t` option, and no longer use `format` in config

closes #698 as well
roxygenize
news for #703, and add @ajdm to contributors
cosmetic
fixed #700: I'm an idiot. Why did I have to check out_format()? Just use knit_hooks$get('plot')
fixes #702: kable() chokes on non-numeric data frames
bump version
fixes #713: ignore \documentclass{} that starts with %