when the protocol is file:, use the http link for the MathJax URL, otherwise use the protocol relative URL
Merge pull request #274 from yihui/bugfix/mathjax-https

Protocol relative URL for MathJax
Revert "when the protocol is file:, use the http link for the MathJax URL, otherwise use the protocol relative URL"

This reverts commit 5ae89ba73945f89a9784e8f07fa1970f9d9dd404.
use the public API in knitr to generate figure filenames
Merge pull request #275 from yihui/bugfix/knitr-figures

use the public API in knitr to generate figure filenames in tufte_handout()
include longtable in tufte handout if there are pandoc tables
Merge branch 'master' of github.com:rstudio/rmarkdown
ensure that files_dir meets requirements for use as a URI in pandoc
bump version