Merge pull request #763 from knokknok/master

fixes #761: only allowing 32 characters (hash length) after label name w...
well, Simon can never remember this; the breakurl problem has come back to CRAN/OS X
knit the notebook in a temp dir, so I do not worry about the auxiliary files
it is hard to believe that I forgot to add the css for syntax highlighting
use the hljs prefix; it does not hurt in this case
tweak the docco_linear style: make the page wider, and use relative font-size for code
apply knit_print() to inline output as well using the new argument inline=TRUE/FALSE

closes #770
document the inline argument, and update the knit_print vignette, explaining the ... argument
roxygenize
bump version
hide the options and inline arguments in the main function, otherwise R CMD check will warn about the mismatch between main function and method
the background color can be set in either latex or html
a helper function pandoc_to() to return the rmarkdown output format
closes #772: add knit_print.knit_asis as an identity function
factor out ncol(x)
closes #771: `digits` can be a vector in kable()
add the chunk option R.options; closes #764
closes #757: use hook_purl to write out code while weaving; this will probably be a breaking change for CRAN
add the chunk option cache.comments; closes #718
roxygenize